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0-C Control Spindle Amplifier Alarms as displayed on Amp:

A0, A1   The control program is not running. Check for ROM not properly
                installed or incorrect ROM. Possible defective PCB.

AL-01   The internal motor temperature is higher than the rating.  
              Check for the motor being overloaded, the cooling fan defective, poor 
              motor ventilation due to dirt or obstruction, motor overheat wires open, 
              invalid detector parameters, motor or thermostat defective.

AL-02   The actual motor speed deviates grossly from commanded speed. 
              Check the load meter to see if the load is too heavy, poor power connections,
              incorrect accel/decel duration parameter setting, incorrect speed detector parameter
              setting, IGBT module/IPM defective, speed feedback signal (cable).

AL-03   The fuse at the DC Link is blown. 
              Check the IGBT module/IPM. 
              This alarm will occur if an over current flows in this circuit.

AL-04   Input fuse blown. Input power open phase. 
             Detects missing fuse or momentary loss of power. 
             Check for open phase and power supply regenerative unit.

AL-05   Control power supply fuse blown. 
              Detects that control power supply fuse AF2 or AF3 is blown. 
              Check for control power supply short circuit.

AL-07   The actual motor speed exceeded 115% of the maximum allowable speed 
              setting (standard speed setting). 
              Check for incorrect speed detector parameter setting. 6511 Bit 0, 1 and 2. For 15 Control 
              it is Parameter 3011 Bit 0, 1 and 2.  For 16/18 its 4011 Bit 0, 1 and2.

AL-08   High input voltage. Detects that switch is set for 200 VAC when incoming voltage is 230.

AL-09   The temperature of the main circuit heat sink has risen abnormally. Check for fan and/or 
              ventilation problem.

AL-10   Low input voltage. Detects drop in input power.

AL-11   Over voltage in DC Link. Detects abnormally high DC power supply voltage.

AL-12   Excessive current flowed in the DC Link, the main circuit power module (IPM) detected an error. 
             Check for a short circuit in the output circuit of the amplifier. The IGBT, IPM or the PCB may be
             defective. Check the model-specific parameter settings.

AL-13   The memory inside the CPU is abnormal. 
              This check is made when the power is switched on. The PCB is probably defective.

AL-15   A sequence of switching operations was incorrect during speed range switching control 
             or spindle switching control. Check the contactor used for power line switching and in 
             particular the auxilary contact.

AL-16   The RAM is abnormal. This check is made when power is switched on. 
              Probably a defective PCB.

AL-19   The offset voltage for the U phase current detection circuit is too high. Check the connection 
              of the power to the PCB, the current detection circuit may be defective, the A/D converter may 
              be defective. In either case the PCB must be replaced.

AL-20   Same as for AL-19 but V phase.

AL-24   The serial communication data between the CNC and Spindle Amplifier is abnormal. 
              Check that the NC power is on, check the serial cable, the LSI chip may be defective or the 
              PCB with the LSI on it, the I/O Link adapter may be defective. This alarm is normal when the 
              NC power is off.

AL-25   Serial communication between the CNC and Spindle Amplifier stopped. Check same as above.

AL-26   The C's contouring control speed detection signal (detector on the motor side) is abnormal. 
             Check the feedback signal level with an oscilloscope, check the connections of the cable, check 
             the cable shield for proper grounding, the detection circuit may be defective, the parameter 
             setting for the C's contouring control detector. It is 6511 Bit 5. For 15 control it is 3011 Bit 5 and 
             for 16/18 control it is 4011 Bit 5.

AL-27   Position Coder signal error. The position coder or it's cable may be defective, signal may be 
              too low (adjust level), feedback cable may not be shielded properly, the detection circuit may be 
              defective. The C's contouring parameter setting may be incorrectly. It is 6501.2 For 15 control it 
              is 3001.2 For 16/18 it is 4001.2

AL-28   The C's contouring control speed detection signal (detector on the spindle side) is abnormal. 
              Check the same as for AL-27.

AL-29   Excessive load (at least 90% of the maximum output as set initially by a parameter) was applied 
              continuously for a certain period. Normally 30 seconds set by parameter. Motor is overloaded, 
              check the load meter, cutting conditions and tool.

AL-30   Input Circuit Over current. Over current flowing in input circuit. Check incoming power for over 
             voltage condition. Possibly bad Power Supply.

AL-31   The motor cannot rotate at the specified speed. It rotates at a very low speed or stops. Check if the 
              motor is physically locked, check if the speed feedback cable is defective, check the speed 
              feedback signal with an oscilloscope, check the power connections.

AL-32   The memory in the serial communication LSI chip is abnormal. The LSI chip is probably defective,
              replace the PCB.

AL-33   Insufficient DC Link section charging. Detects insufficient charging of DC power supply voltage in 
              power circuit section when magnetic contactor in amplifier is turned on. Check for open phase or 
              defective charging resistor.

AL-34   A Parameter setting is invalid, check parameters.

AL-35   The value set in the gear ratio data parameter is greater than the limit allowed in the internal processing.
              Incorrect gear ratio parameter setting, check if the specified gear ratio is too high. Spindle to Motor Gear
              Ratio Parameter 6556 to 6559. For 15 controller it is 3056 to 3059. For 16/18 control it is 4056 to 4059.

AL-36   The error counter overflowed. Check if the values set in the gear ratio and position gain parameters 
              are too large. Check parameters above as well as 6560 to 6563 (Position gain during orientation), 
              6565 to 6568 (Position gain during servo mode/synchronization control of the spindle), 6569 to 6572 
              (Position gain during C's contouring control).

              For 15 controller: 

              3060 to 3063
              3065 to 3068
              3069 to 3072

              For 16/18 controller: 

              4060 to 4063
              4065 to 4068
              4069 to 4072

AL-37   When an emergency signal was entered, the motor did not decelerate, rather it accelerated or the 
              motor was kept excited even after the accel/decel duration time (normally 10 seconds as set by 
              parameter). Check that the speed detector parameter, 6511.0,1 and 2, is set for the speed detector 
              used. 3011.0,1 and 2 for 15. 4011.0,1 and 2 for 16/18. Check that the Accel/Decel duration parameter, 
              6582, is set correctly. 3082 for 15. 4082 for 16/18.

AL-39   The C's contouring control one rotation signal has not been detected correctly. Check that the feedback 
              signal level is sufficient and that the shield is properly grounded. Check that the parameter used 
              to specify the use of the C contouring control detector, 6503.4,6 and 7 is set properly. 3003.4,6 and 7 
              for 15. 4003.4,6 and 7 for 16/18. 
              PCB may be defective.

AL-40  The C's contouring control one rotation signal is not generated. 
             Check the cable and signal as above. 
             Check the offset of the C's contouring control one rotation signal with an oscilloscope and adjust as 
             necessary. PCB may be defective.

AL-41   The position coder one rotation signal was not detected correctly. 
              Same as AL-39.

AL-42   The position coder signal was not generated. 
              Check cable, shielding, position coder, PCB, etc.

AL-43   The position coder used for the main spindle during the differential speed mode was disconnected. 
              Check cable, shield, coder, etc. Check parameter 6500.5 (Setting for Differential Speed Mode 
              Functions).   3000.5 for 15. 4000.5 for 16/18.

AL-44   An A/D Converter error occurred. A/D Converter is probably defective, replace the PCB.

AL-46   The position coder signal was not detected correctly during thread cutting. 
              Same as AL-39.

AL-47   A pulse count for the position coder signal is abnormal. 
             Same as AL-39.

AL-49   During Differential Speed Mode, the sub-spindle motor speed converted from the main spindle motor 
              speed exceeded the limit. The differential speed is calculated by multiplying the main spindle motor 
              speed by the gear ratio. Make sure that the calculation does not exceed the maximum motor speed.

AL-50   During the synchronization control of the spindle, the calculation result for the speed command 
              exceeded the limit. The motor speed command is calculated by multiplying the spindle speed 
              command by the gear ratio. Make sure that the calculation result does not exceed the maximum 
              motor speed.

AL-51   Under voltage at DC Link section. Detects that DC power supply voltage of power circuit has dropped.

AL-52   ITP signal abnormality 1. Detects abnormality in synchronization signal (ITP signal) with CNC.

AL-53   ITP signal abnormality 2. The ITP signal (Sync Signal for Sync With the CNC) stopped. CNC error, 
             check the operation of the CNC. Serial communication LSI chip may be defective. If so, replace the PCB.

AL-54   It was detected that a high current flowed in the motor for a long period. Motor is overloaded or 
             accel/decel is too frequent. Check the load meter for overloading. Check if accel/decel was repeated 
             very frequently. Check cutting conditions.

AL-55   During spindle switching control or speed range switching control, there was a conflict between the 
              switch request signal (SPSL or RSL) and the power line state confirmation signal (MCFN, MFNHG, 
              or RCH, RCHHG). Switching unit (magnetic contactor for power line switching) may be defective. 
              Connections of magnetic contactor may be loose. Make sure the Parameters for the power line state 
              signals related to the spindle switch control and output switch control are set correctly.

             6514.2 = Specifies the power line state signal for spindle switching control. 
             3014.2 for 15 and 4014.2 for 16/18.

             6514.3 = Specifies the power line state signal for speed range switching control.
             3014.3 for 15 and 4014.3 for 16/18.

AL-56   The cooling fan for the control circuit stopped. The cooling fan is probably defective.

AL-57   Control circuit is erroneous. Check connections and incoming AC. The Spindle Amplifier is probably 

             Accel/Decel Duration Parameter = 6582  
             For 15 Controller it is Parameter 3082 and 16/18 Control its 4082.

             Speed Detector Parameter = 6511 Bit 0, 1 and 2  
             For 15 Controller it is Parameter 3011 Bit 0, 1 and 2. For 16/18 its 4011 Bit 0, 1 and 2.

0-C Control Power Supply Alarms as Displayed on Power Supply:

01      The main circuit power module (IPM) has detected and error.(PSM -5.5, -11) Over current flows into the  
           input of the main circuit.(PSM -15 to -30) The IGBT (or IPM) is defective, replace. The specification of the
           AC Reactor does not match the Power Supply Module. Check the PSM and the specification of the AC  

02       A cooling fan for the control circuit has stopped.
           Check fans for proper rotation.

03      The temperature of the main circuit heat sink has risen abnormally. Check cooling fan and proper  
           ventilation of unit. Also check for overloading of the system.

04       In the main circuit, the DC voltage (DC Link) has dropped.
           A small power dip may have occurred. The input power may be too low.
           The main circuit power supply may have been switched off with an emergency stop state released. 
           Check the sequence.

05      The main circuit capacitor was not recharged within the specified time. 
           Too many SVM and/or SPM (Servo and/or Spindle) units may connected. Check the specification of the 
           PSM. The DC Link may be shorted. Check the connections. The recharge current limiting resistor may be
           defective. Check the wiring board.

06      The input power supply is abnormal (Open phase).

07      In the main circuit, the DC voltage at the DC Link is abnormally high. The regenerated power may be
          excessive. In this case, regeneration is impossible, the PSM does not have the capacity. The output   
          impedance of the AC power source may be too high. Check the output impedance. The regeneration 
          circuit may have failed. Check whether there is an Over voltage at check terminal IR or IS. May be 
          necessary to replace wiring board or PCB. The IGBT (or IPM) may be defective.

If a machining center will not allow you to move any of the axes in MDI or PROGRAM unless the spindle is running, you can change Parameter 24.2 (SCTO) to 0. This tells the NC not to check for the Spindle Speed Reached Signal.

The 900 series parameters on the O control are for Optional Parameters.

If a control indicates Alarm 407, 417, and 427 (Serial Servo Alarm for X,Y,Z) at the same time, the Memory is probably scrambled. Once scrambled, it must be cleared by cycling power and holding the Reset button. Remember to try this first without holding the Delete button to avoid clearing the Programs until it is absolutely necessary. If you must clear the entire memory, backup the programs and offsets first. To do this you may have to cycle the power while holding the Reset button. Then, enter the 900 series Parameters by hand, cycle power normally, enter the communication parameters by hand (10,552,etc.) Then backup up programs and offsets, then clear the whole memory by cycling the power while holding the Reset and Delete buttons. Anytime the memory is cleared, no matter what method you will use to re-enter the parameters, you should enter the 900 series first then cycle power normally, then enter all the other parameters. When entering the 900 series the control will give a 000 Alarm telling you to cycle power. You should cycle power each time this happens rather than waiting until all 900s have been entered. You will also receive alarms when loading the 900 parameters by hand telling you that the action you have chosen will destroy files. You have no choice but to continue on. If you do not so me of the 900 series parameters will not be entered and the control will not be properly set up. Normally, after losing the memory you will have Servo alarms which will prevent you from loading the parameters with a PC. These alarms are generated because when the memory is lost the Motor Model I.D. parameters 8120,8220, and 8320 to go to zero. The alarm results because zero is not a valid Motor I.D. number.

What you must do is:
1. Load the 900 parameters by hand.
2. Enter the motor model I.D. ( Parameter 8120,8220,8320 for X,Y,Z)
3. Make Parameter 8100.1,8200.1,8300.1 = 0. (This will cause the control to power up with the default values for
    the Motor model selected in Parameter 8120,8220,8320 which will prevent the alarms.)
4. Cycle power.
5. Now the Digital Servo Parameter alarms should go away and you should be able to load the rest of the 
    parameters with the PC.

If you want to reload the parameters by RS232 but the alarms prevent it, try pressing the EOB button with INPUT.

Any time you are loading the parameters by hand it is helpful to set P64.5 to equal 1 so that the control won't switch from the Parameter page to the Alarm page every time the 000 Alarm is issued.

An important Parameter to be aware of is Parameter 38 bit 3. This bit should normally be a 1. If it is 0, the Data Search function is disabled so you will have to find parameters by paging through. Power must be cycled after this parameter is changed. Parameter 38.3 (FLKY) is the parameter which selects a full keypad or not. If you have a full keypad and this parameter is set for 0 instead of 1, the search function along with other features unique to the full keypad will be disabled.

An alarm that is commonly issued when parameters are lost is 520. This is an over travel alarm. Normally, you can get rid of it by setting parameter 15.2 to 1.

Another thing you will likely see when Parameters are lost is Alarms 410, 420 and 430. These alarms indicate a Position Deviation Error while machine is in a stop state. They correspond to X, Y and Z. These alarms will occur in cases where Parameters 593, 594 and 595 are lost. This is because the control is being told that it's maximum allowable position deviation is zero. This represents an unreasonable quantity. If you are trying to reload the parameters, you can remove the alarms by manually inputting the 593, 594 and 595. The Setting Range is 0 to 32767. These values are typically 500.

Pressing the E-Stop will not help with Serial Alarms such as 408 and 409. In the case of the 409 alarm, depending on the control you may get rid of this by setting Parameter 100 to it's proper value. Parameter 100 is the CMR (Command Multiply Ratio) for the X axis on both a T and M Control.

You may also get an Over Travel Alarm that won't go away if one of the axes is sitting on the reference switch when parameters are lost. You can often remove this alarm by setting Parameter 38 bit 0 to it's proper value. This bit changes the Input Address of the Deceleration signal on a T Control. If P38.0 = 0, the signals will be taken at X19.7 for DEC3 and X19.5 for DEC4. If P38.0 = 1, the signals are taken from X16.7 for DEC3 and X17.7 for DEC4. Parameter 38 also has to be set for proper communication to allow the loading of Parameters via RS232.

Setting Parameter 71.7 may cause Alarms 408 and 409 to issue but is nothing to be concerned about.

Normally when you change a parameter and receive the 000 alarm, you should go ahead and cycle power. The one exception to this is when loading the 8000 series parameters. If you change Parameter 8100, 8200 and 8300 for an M control, you get the 000 alarm. If you cycle power the control changes the parameter back so what you must do is set the whole series 8100 to 8200,8200 to 8300, etc., then cycle power. You may find this procedure necessary on other series of parameters as well.

Parameter 60.7 selects either color or monochrome display if you have a 9" CRT so if when you correct this parameter you will notice a big difference when you power back up. That is, if the control is equipped with a color CRT. So, if you lose parameters, don't be shocked when the monochrome display appears, it is temporary. 
P60.7 = 0  Monochrome Display P60.7 = 1  Color Display

Sometimes you may have to work with Password Protect Parameters 797 and 798.

Servo Motor Parameters can be set up automatically if necessary. This is known as Auto Tuning. If you know the motor model I.D. you can enter it into Parameter 8120, 8220 or 8320 for X,Y or Z then change 8100.1,8200.1 or8300.1 to zero and cycle power to load the Fanuc motor default values.

The improper setting of any of the following parameters can cause a 4n0 of 4n1 alarm:


If Alarm 4n4 occurs continually, check the following parameters:

8100 Series

For Axis Feed rate problems check Parameters 


Parameter 556 sets the maximum spindle speed in G96 (Constant Surface Speed). G97 cancels Constant Surface Speed Control.

If the Servo Setting Screen can not be displayed make sure that Parameter 389.0 = 0. For 16, 18, 20 and 21 controls it is Parameter 3111.0 = 1.

If an axis won't move in Jog mode on a 0 control you can give a move command in Jog mode while checking Diagnostic 116. This diagnostic indicates if the ladder (PMC) is sending the jog command to the CNC side.

To do a Forward Ladder Search on a 0 control, enter the address (i.e. Y82.2) and press INPUT.

On most 0 controls turning the NC power off while uploading or downloading programs will cause Alarm 101 to be issued when power is turned back on. If this happens you must clear the Program Memory.

On some 0 controls Diagnostics cannot be output.

1.  Switch to MDI mode.
2.  Engage the Emergency Stop.
3.  Press the PARAM key.
4.  Press the Page Down key.
5.  Cursor to PWE.
6.  Press 1.
7.  Press the INPUT key.
8.  Press the Page Down key until you reach parameter number 900.
9.  Using the paper copy, enter all of the 900 series parameters.
      (It is not necessary to enter the entire parameter. For example the parameter 00001000 can be entered as  
      1000, the parameter 00011100 can  be entered as 11100 etc.)
10. At this point all other parameters can be entered.
11. Change PWE back to 0.
12. Power the control off and back on.

The M Code for Spindle Orient takes the form of a parameter usually P587.

If a 8. is displayed on a 0 Control Servo Amplifier There is an excessive current flowing in the output section of the servo amp. Disconnect the motor leads, if the alarm goes away the motor is shorted etc. If the alarm does not go away, there is an internal problem with the amplifier.

When working on problems with Servo or Spindle alarms, be sure to distinguish between information about velocity feedback and position feedback. This is especially important with the Spindle because there are normally more than one encoder involved, the motor encoder for velocity feedback and the orient pulse coder for position feedback. For example Alarm 409 refers to a loss of POSITION feedback so if you start chasing the motor encoder and cables you will waste a lot of time.

Typical cable configurations for 0C:

Spindle Amplifier:

JX4  -------------- EMPTY

JX1A ------------- JX1B (POWER SUPPLY)

JX1B ------------- JX1A (SERVO AMPLIFIER)

JY1  --------------- ?

JA7B ------------- OPTICAL I/O LINK ---------- COP5 (MEMORY BOARD)

JA7A ------------- EMPTY

JY2  -------------- ?

JY3  -------------- EMPTY

JY4  -------------- ?

JY5  No Plug

Servo Amplifier:

JX5  -------------- EMPTY

JX1A --------------JX1B (SPINDLE AMPLIFIER )

JX1B ------------- DUMMY PLUG

PWM1 ----------- M184 (AXES BOARD)

PWM2 ----------- M187 (AXES BOARD)

PWM3 ----------- M194 (AXES BOARD)

Axes Board:
____________________________ PWM2 (SERVO AMPLIFIER)
|                             JV2B
M187       M184 -------------- PWM1 (SERVO AMPLIFIER)

M197       M194 -------------- PWM3 (SERVO AMPLIFIER)
|                             JV3B

____________________________ Y AXIS PULSE CODER
M188       M185 -------------- X AXIS PULSE CODER

M198       M195 -------------- Z AXIS PULSE CODER

Memory Board:

M27 ------------- EMPTY

M12          M26 ------------- EMPTY

M3           CCX5 ------------ ?

M5           M74 ------------- EMPTY (COM PORT)

COP5 ------------ OPTICAL I/O LINK
CPA7 ------------ BATTERY PACK

On a 3 axis servo amplifier the output wiring normally appears as:

           X                                     Y                                   Z

RED        WHITE           RED        WHITE         RED       WHITE


In addition to the alarm indicator, the PSM is equipped with five check
terminals. Below are their designation, positions, and normal values:

IR            Corresponds to L1 (Phase R)
IS            Corresponds to L2 (Phase S)
+24V      Control Power +24vdc
+5V        Control Power +5vdc
0V          Control Common 0vdc

The nominal value of IR and IS will vary according to PSM model. Below is a
a list corresponding to available models:

Model                   Nominal Value             Over current Alarm Level

PSM-5.5               25A/1V                        Depends on IPM alarm output
PSM-11                37.5A/1V                             "         "   "         "          "
PSM-15                50A/1V                        300A/6V
PSM-26                75A/1V                        450A/6V
PSM-30                100A/1V                      600A/6V

IR and IS are check points which output a voltage proportional to the amount of current being drawn from the power supply. So on a PSM-11, for example, if you measure from Pin IR to Pin 0V and see 2vdc, the PSM is supplying 75 amps.

If the PIL indicator is off, check the +5V power circuit because the PIL circuit operates off of +5vdc.

An A Model control will not display the Ladder nor will it output the Diagnostics via RS232.

If you have an intermittent problem with a machine and you suspect that a switch is making or breaking when it is not supposed to or some other signal is changing states to cause the problem, you can set a trap to catch the signal changing. This trap will catch any bit that changes states in Diagnostics 000 to 699. To set the trap:

1. Go to Parameter 25 and clear it out (Change all bits to 0).
2. Go to Parameter 578.
3. Add 59344 (A constant) to the number of the Diagnostic you want to trap.
4. Enter this value into Parameter 578.
5. When the machine malfunctions go to Parameter 25.
6. A 1 will appear in the bit corresponding to the bit of the signal which changed states. This bit will remain set 
    even if power is cycled.


If you had a machine which was mis-positioning and you suspected the cause to be noise on the MLK (Machine Lock) signal G117.1 causing it to go high and cause a problem. You would go to Parameter 25, clear it out. Go to Parameter 578 and input 59461 (117+59344). The number 6075 will appear on the CRT. This is the result of 65536(Another Constant) minus 59461. Parameter 25 will now reflect any change in states of G117. The 8 bits in P0025 will correspond to the 8 bits of G117. So if you want to know if MLK changed, look at Parameter 25.1.

You can monitor more than one signal at a time because Parameter 579 and 26 work together in the same manner as 578 and 25.

The maximum amount of memory for a 0 control is 320 Meters which is 128 K Bytes.

To access the Macro Variables press the OFSET button and then the MENU soft key.

Parameter 636 stores the value of deceleration.
Parameter 59.1 and 59.4 are for Deceleration Function Active in G0 and G1.

Zero controls look ahead two or three blocks. When you have an alarms or other problem you may be able to catch it by using single block. When a program hangs up, the problem may be in the portion that was read ahead, two or three blocks from where the cursor is.

This screen is also available on some 0 controls. To access the screen:

1. DGNOS/PARAM button.
2. SP-PRM soft key.
3. SP. MON soft key.

For problems involving the RESET button on a zero control you can try working with Parameter 391.7 (NOCLR) and P45.6 (CLER). Both of these parameters have to do with what happens when the RESET button is pressed. Certain settings will cause some Modal commands to be cleared when it is pressed, for example. The same thing is true with Parameter 2401.7 (NCM) on a 10 control.

Also keep in mind that 4n4 (in the case of 0 control) is one of those alarms that you can check Diagnostic number D721 for an indication of what the problem may be. In the example above, a 1 would be displayed at bit 4 of D721 (HCAL).

When working on machines like a Yang that uses a 0-TD or 0-MD control, keep in mind that they may not have an EDIT key (hardware) to prevent editing of programs. In this case you have to use the KEY function of the Software Operators Panel.

On machines that do not have a program protect key, press the Alarm button three times to access the Setting screen and toggle the KEY with arrow buttons.

Normally in order to either type in or load the Diagnostic Parameters via RS-232 you must have the Edit Key turned off (edit enabled). If not, you will be able to type the Diagnostics in but when you press the
Input button, they will be removed from the screen but the value will not change.

In order to clear the program storage memory area of a zero control you must first turn on the PWE then hold the DELETE key while the NC is powering up.

For alarms 502 and 503 on a machine with the 0i control, make sure the second or third stroke limits have not been turned on accidentally. The parameter is 1310.0 for the second stored limits and 1310.1 for the third. 1 turns the limits on and 0 turns them off.

The drivers for RS-232 on some 0 control memory boards will be 75C188 and 75C189 instead of 75188 and 75189. These chips will be surface mount instead of PDIP.

You can be fairly certain if there is a problem with the drives, I/O board, even CPU or system software causing a Not Ready state, the control will be aware of it and will issue either an NC alarm or show an alarm number on a drive LED display or both. If the machine is NOT READY but no alarms condition is indicated by the control, then the Not Ready state is being caused by something external to the control. The only exception may be a failure of the Ladder (PMC) software or it's firmware but this is extremely rare. If the control checks out, check the E-Stop circuit. Does the machines E-Stop circuit check out to the extent that there appears to be no external E-Stop being generated? With most machines, as in the example above, you can determine if the this circuit is ok by checking the potential across terminals 1 and 3 of connector CX3. The E-Stop circuit will either close to supply voltage to CX3 or will close to pass the voltage from CX3 to MCC. You can also short across the two CX3 terminals to see if the machine becomes ready but you must be careful since the PMC may have the machine in a NOT READY state and forcing MCC on could cause serious damage. Now, if the drives and the E-Stop circuit check out, turn your attention to the PMC. The way that E-Stop is generated through the PMC is by acting on the signal *ESP. The address for *ESP is X21.4 on the machine side and G121.4 on the CNC side. This should always equal 1. If X21.4 is 1 but G121.4 is 0, the E-Stop circuit is ok but this is not being relayed to the CNC. With most machines, as above, the same components that complete the circuit for MCC also supply the input to X21.4 but some machines will use different circuits for the two. X21.4 (*ESP) and G121.4 (*ESP) must be 1 for the machine to be in a READY state. G121.5 (*SP) is the Feed Hold signal, it should also be 1. When the machine is in E-Stop this will be 0. Don't let it sidetrack your troubleshooting. In addition to the above circuitry, you must be aware of CX4. CX4 of the Power Supply Module also will place the control in a Not Ready condition. In order for the control to be in a ready state, pin 3 of CX4 (+24V) must be connected to pin 2 of CX4 (ESP) through some external circuit. In the case of the example above, this is done with a normally open contact (pins 5 and 9) of KA24. To sum up. in order for a machine to be in a Ready state, pins 2 and 3 of CX4 must be connected, pins 1 and 3 of CX3 must be closed within the Power Supply Module and X21.4 must be 1.

An important parameter to be aware of is parameter 452 for the X axis, 453 for the Y axis and 454 for the Z axis. Fanuc calls these secret parameters. What they do is store the number of pulses recorded for the Absolute Pulse Coder when it is at home. If you replace an absolute pulse coder you can reset the zero point without working with this parameter and the machine will run but off the wall intermittent problems can occur. For example, the machine may have over travel alarms when powering up even while the machine is in the middle of it's travel. Also, an axis may misposition but only once every few days, weeks or months. Another situation that might arise is the machine will pick up the correct offset 99.99% of the time but once in a blue moon will not. Glen says he has seen cases where resetting the parameter will fix the problem. The parameter is reset by changing it to zero and zero returning the machine. The control will give the 000 alarm so you will have to cycle power.

Troubleshoot alarm 3n9 with Diagnostics 760-767 and 770-777. Diagnostics 760 for first axis; 761 for second axis; 770 for first axis; 771 for second axis, etc.

760-767    7          6          5           4            3           2           1           0
                          CSAL   BLAL   PHAL     RCAL   BZAL    CKAL    SPHL

CSAL  The serial pulse coder is defective. Replace it.

BLAL  The battery voltage is low. Replace the batteries.

SPHL  The serial pulse coder or feedback cable is defective. Replace the serial pulse coder or cable.

RCAL  The serial pulse coder is defective. Replace it.

BZAL  The pulse coder was supplied with power for the first time. Make sure that the battery is connected.
            Turn the power off, then turn it on again and perform a reference position return.

CKAL  The serial pulse coder is defective. Replace it.

PHAL  The serial pulse coder or feedback cable is defective, replace the pulse coder or cable.

770-777         7               6                 5              4              3             2              1             0
                  DTERR  CRCERR    STBERR

DTERR     The serial pulse coder encountered a communication error. The pulse coder, feedback cable or 
                   feedback receiver circuit is defective. Replace the pulse coder, feedback cable or NC axis board.

CRCERR  The serial pulse coder encountered a communication error. The pulse coder, feedback cable or  
                   feedback receiver circuit is defective. Replace the pulse coder, feedback cable or NC axis board.

STBERR    The serial pulse coder encountered a communication error. The pulse coder, feedback cable or
                    feedback receiver circuit is defective. Replace the pulse coder, feedback cable or NC axis board.

In order to retrieve data from a variable, you have to execute a macro program. For example, to find the 
number of hours the machine has been run (cycle start lamp on):

G65 P9100;


The run time data is stored in variable 3002 but can not be directly viewed. This is the only way to access it. After running program O3737, you can go to variable 500 (#500) and read the data.

On the 18 control the same procedure works (#500=#3002) but the control has to have CUSTOM MACRO B. Anytime a machine does not want to execute a function, especially in MDI, spindle start, feed rate commands, override, MPG, etc, try doing the same function from the CRT/MDI and/or the Software Operators Panel instead of the machine operators panel. If the command or function works by the CRT/MDI or Software Operators Panel but not the machine panel, it may point to a problem with the machine panel, power supply to the panel, wiring or even the ladder.

Some information in the control is stored in the form of System Variables. These variables store things such as the amount of time the Cycle Start lamp has been on, the current axes position, current time, date. Some alarms are stored in system variables. These variables and their values cannot be seen or accessed directly. Generally speaking, the only variables which can be seen or manipulated are Common Variables. These variables are numbered from #100 - #149 and #500 - #531. As an option, #150 - #199 and #532 - #999 are available. Variables #1 - #33 are local variables. They an only be used within a Macro to hold data such as the results of operations. When the power is turned on, these variables are set to null. When a macro is called, arguments are assigned to local variables. System Variables are numbered from #1000 and up. If you need information stored in a system variable and you know which one it is stored in you can access it by moving it from the system variable address to a common variable address. This is done by writing and executing a program. What follows is an example of how to access how long (in hours) the Cycle Start lamp has been turned on.

#500 = #3002;

This reads like (Variable 500 equals variable 3002).

The # and = symbols are entered by pressing the SHIFT key. In the case of #, press SHIFT then M. For =, press SHIFT then S. When you press the SHIFT key you should see this symbol displayed ^. If it is not displayed, there is likely a problem with the keypad.

After running the program, the value stored in #3002 can be seen by looking at #500. In order to see #500:

1. Press OFSET button.
2. Press MACRO soft key.
3. Page to #500.

When a value is moved from a variable to #500 it replaces whatever is already there.

The value of Common Variables can be changed to another value including 0. To do this, cursor to the variable, type the desired value, press INPUT. This can be done from any mode.

If G98 does not allow the axes to move without the spindle running, make parameter 24.2 =0.

To change the accel/decel time of the spindle motor use parameter 6580. A typical setting for this parameter is 70.

If a control locks up so that nothing on the keypad or operator's panel works while a DNC operation is underway, the problem is probably the PC, cable or communications software. Of these three the most likely one is the cable. You must be careful when using the usual troubleshooting methods. Normally when a control freezes during program execution you can check Diagnostic 700 to find out why but in this case if the machine was in motion when the cable caused the lock up, you may well see bit 3 (CINP) is turned on but the In-Position check is not the cause of the lock up but simply a symptom.

For rigid tapping problems on a machine with a 0M control look in the Operation and Maintenance Handbook, there is an entire section of parameters just for rigid tapping. If you don't have the handbook check parameters:


In particular look at parameter 688, this is the parameter for backlash compensation only during rigid tapping. Keep in mind that other problems can be backlash in the spindle motion, that is, delay in reversing direction due to belts, gears, etc. Also, check the separate pulse coder, it's belt could be slipping, etc.

To enable/disable Feed Hold and Single Block in rigid tapping, parameter 397.3 (RGMFH). 0 for enable, 1 is for disable.

Most of the time if you are working with a 0-Mate control, there will be no Ladder display. In some cases you can turn the ladder on by changing bit 2 of parameter 60.

Be careful changing parameter 38, there are some bad things that can happen. If you set 38.3 wrong it may cause the CRT to not display data as it is entered.

The Axis Servo Motor information is stored in Parameters 8100-8125, 8200-8225 and 8300-8325 for X,Y and Z.

In order to use more than one M-Code in the same block, make Parameter 65.7 equal 1.

On some 0 and 18 controls, the Work Shift Coordinate is not shown on a separate page but rather on the Work Coordinate page. When on this page it may show up as


NO.  (SHIFT)               NO.   (G55)
00    X _.____             02      X _.____
        Y _.____                       Y _.____
        Z _.____                       Z _.____

NO. (G54)                 NO.   (G56)
01    X _.____           03      X _.____
        Y _.____                     Y _.____
        Z _.____                     Z _.____

Fanuc, GE Fanuc, and General Numeric controls are basically the same. For example, a General Numeric GN0 is for all intents and purposes a Fanuc 0. Generally speaking, the manual numbers, part numbers, etc. are all the same. The only difference is in the first few characters. As an example, the part number for a Fanuc 0 Operators Manual is B61404E. The same manual for a General Numeric GN0 is GN61404E and GE Fanuc 0 control is GFZ61404E.

ATC Macros are 9000 programs and cannot be sent or received unless Parameter 10 Bit 4 is zero. If you 
have ATC trouble you may want to check the 6500 series parameters.

Setting Parameters REVX and REVY should both be 0 under normal conditions. When set to 1 the axis direction will be reversed. One condition that can arise from this setting being wrong is that when a program is started and the axis tries to move to the G54 position it may travel until the soft limit is reached. This over travel condition is a result of the mirror image function. Setting the parameter back to 0 will fix the problem but you must perform reference point return after changing the parameter.

When you are loading Parameters or Diagnostics via RS232, you should see LSK flashing after you press INPUT until the control begins receiving the data. Once the data is present at the input of the control, you should see INPUT start flashing.

When Parameter SEQ (On the Setting Screen) is set to 1 the control will insert the sequence numbers automatically.

In order to receive parameters and diagnostics at the PC in text form you must make EIA/ISO = 1 (ISO). 

If you can upload but not download or vise versa, there is almost definitely a hardware problem with the Memory board.

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The information on this and subsequent pages is intended to supplement and reinforce the knowledge of competent machinists and technicians. The authors of this website are in no way lialble for damage or injury resulting from the improper use of the instructions contained herein.