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GE Fanuc Hotline Charlottesville         800-828-6151

GE Fanuc Fax on Demand                   804-978-6883

Fanuc USA                                            888-326-8287 (888-FANUCUS) 
Fanuc Technical Sales Fax#                 847-898-5006

Another source for Fanuc parts is:
615-459-2848   Fax 615-459-7917

817-469-7797   Fax 817-460-1553
2627 S. Cooper Street
Arlington, TX 76015

A good source for cables is Machine Tool Services. Their number is 480-985-1941. They can make the motor and feedback cables to length.

When a machine doesn't position correctly it can sometimes be because of electrical noise on the MLK (Machine Lock) signal.

The breakdown on the Fanuc part numbers is:
i.e. A06B-6079-H203#EM
A06B Identifies part as either a Motor or an Amplifier.
6079 Identifies Series, Serial or Digital.
H203 Identifies physical size and Capacity.
#EM  Identifies part as one approved for the European Community (CE).

It is possible to troubleshoot with the Ladder even if you have a controller that does not display it. If you have a hard copy of the ladder, you can follow the instructions as you normally would by looking for the addresses in the diagnostics. For example:

-------| |-------------|/|------------------------------(  )------
   R551.2       F126.0                               Y8.1

All of these can be found in Diagnostics.

0551   00000X00  =   R551.2
0126   0000000X  =   F126.0
0008   000000X0  =   Y8.1

If the instruction is --| |-- the corresponding diagnostic bit must be 1 for the instruction to be true.

If the instruction is --|/|-- the corresponding diagnostic bit must be 0 for the instruction to be true.

X and Y bits are checked the same as usual.

This is how a Box works in the Ladder:

                        |              |              |                |                        |
                        | SUB      |   2         |   3000     |      R673         |
         --| |---|/|---| 24         |              |                |                        |-----------( )----
                        |              |              |                |                        |

The first block identifies the box as a fixed timer.
The second block denotes the timer number.
The third block indicates the value of the timer in milliseconds.
The fourth block indicates an address which is acted upon by the timer.

The following is an example of a M Code box:
               | SUB 4    |    F151                                              |
               | DEC       |                                                          |
               |                |                                                          |
               |                |                                           8411       |

The first block identifies the box as a Decode module.
F151 is the address where the M Code is stored and will change with different\
M codes.
84 is the M Code designation (M84).
11 indicates what part of the M Code is to be decoded in this module
   11 = Decode both High Order and Low Order (8 and 4)
   10 = Decode High Order (8) only
   01 = Decode low Order (4) only
   The High Order can be decoded in one box and the Low Order in another.

The M Code is stored as BCD. 84 = 10000100

If a controller comes equipped with RAM chips, they must remain on the memory board. If they are removed, a RAM Parity Error is issued and will not go away even if you hold RESET/DELETE at power up. 

The Fanuc Software Edition is the big number at the top of the first boot-up screen. Normally something like O667-****.

If the Absolute Position display resets to all zeros when the RESET button is pressed, check the MAN/ABS button. If it is set to MANUAL, the display will reset to zero depending on parameter settings.

If INCH = 0 on the Setting page the machine will be in Metric. It will interpret a numerical command as metric (i.e. G1 X50.0 equals 50mm). The position display will also be in Metric. If set to 1, the machine will be in Inch. This setting can be changed at any time, power does not have to be cycled.

One Kbyte of memory is equal to 1000 characters. When Fanuc sells memory, they sell it by the Kbyte. They will sometimes talk about memory in terms of Meters.

For most Fanuc controllers the ON/OFF switches on the CRT/MDI plug into the Input Unit. When you press the ON button, you are turning on the Input Unit. If everything is OK with the Input Unit and the controller in general, the Input Unit will latch through itself and the NC will come on and stay on. If there is a problem in the power circuits, it will not latch. Depending on the problem it will come on then shut off or not come on at all. Problems can be diagnosed based on which of these scenarios occurs.

The Fanuc equivalent to Mitsubishi Axis Release is Axis Detach.

The drive components of most Fanuc controllers are the same so the troubleshooting methods, Not Ready alarm, etc., shown below can be used.

When the main power is turned on the PSM (power supply module) displays two dashed lines, (steady) the Servo Amplifier displays a single dashed line, the Spindle Amplifier goes through it's sequence of displaying it's software information (normally a string of three) after which it displays two dashed lines (flashing). Now the NC power is turned on with the E-Stop in. The Spindle Amplifier display stops flashing, displays the two dashed lines on steady. The PSM and the Servo Amplifier display do not change. Now the E-Stop is pulled out. The PSM display goes immediately to 00. The Servo Amplifier display goes immediately to 0. If a spindle run command is entered such as pressing the CW or CCW Run button or entering M03, M04 etc., the Spindle display goes to 00 (steady). The spindle does not run because no speed command has been entered. The spindle speed setting is reset when power is cycled. If the spindle stop is pressed or Reset, etc., the Spindle display goes to two steady dashed lines. If the spindle run and spindle speed command are entered, the display goes to 00 and the spindle runs. If the E-Stop is pressed, the display goes to two steady dashed lines. If the NC power is turned off the display goes to 24 and the red LED (ALM) comes on.

Under normal operation, if you watch the PSM when the main power is turned off, you will see 02 displayed briefly and the ALM (red) LED will turn on for an instant.

When a machine is in a NOT READY state, there are three things to look at.

1. Are the drives and other control hardware and software ready?
2. Is the E-Stop activated?
3. Is the PMC generating a Not Ready condition?

If the memory becomes scrambled or is partially lost, the memory board must be cleared. In most cases it is only necessary to clear the parameter and offset memory, but sometimes the program memory must be cleared as well. 
The procedure for clearing the parameter and offset memory is as follows:

1. Turn power to the controller off.
2. Press and hold the RESET key.
3. Turn the power back on.
4. Hold the RESET key until the screen comes up.
5. Release the RESET key.

If the controller will not come up, repeat the procedure holding the RESET key and the DELETE key while powering up. Should it ever be necessary to clear only the programs, perform the procedure holding only the DELETE key. In order to clear the program memory by powering up with the Delete key pressed, PWE may need to be set to 1.

If you do this you will lose all programs including the ATC Macro program. 

The procedure for re-entering the parameters varies depending on the media at your disposal. (i.e. Handy File, PC with Procomm, etc.).
All end users should have at least one paper copy of the original parameters. If the end user does not have access to any of the media mentioned above, it will be necessary to load all of the parameters by hand. This method will take about an hour and require a lot of key presses. The procedure is:

Pressing and holding the P key and the CAN key while powering up the controller tells the CNC to ignore the programmed stroke (soft) limits. The CNC will ignore these limits for as long it runs until the machine is homed (ZRN). Any time this procedure is used, for example, to clear an over travel alarm the machine should be zero returned.

A "D" address in the controllers memory is a location in a data table. A Data Table is an area of memory set aside by Fanuc for the machine tool builder to store information to be accessed by the program..

On the SETTING page, making INCH equal 1 causes the display read in English while zero causes it to read in Metric. Either way, the actual measuring is not affected.

On some machines turning the NC power on will cause one or more of the servos to jump as much as .0003" due to shielding or other power problems. The display will zero when RESET is pressed.

Never turn off the NC power while data is being input via RS232. If this is done while inputting a program, the program memory will be scrambled and will have to be cleared. If you are communicating with the controller and wish to terminate, it is best to physically break the RS232 connection.

The maximum allowable voltage deviation on Fanuc controllers is -15% and +10%. Both the 5vdc and 24vdc outputs of the Power Supply must remain within +/- 5% to prevent an alarm.

If when trying to communicate with a Fanuc controller using Procomm, the data flows very slowly, check the setting for delay between characters and the setting for delay between lines. Sometimes it is necessary to put a value in one of them in order to communicate with a Mitsubishi or other controller but it will cause a Fanuc to slow way down. When working with a Fanuc, these should probably be set to zero.

The number of data bits for RS-232 communications on all Fanuc controllers is set at 7 and cannot be changed.

All communication between the NC and its I/O boards is serial whether through conventional wiring or fiber optic connection going all the way back to the 5 and 6 controllers. This means that if the status bits (Diagnostic or Ladder) show an Input (X) or Output (Y) going high you can be sure that this is communicated to and/or from the I/O board unless there is a complete failure of this circuit. In that case there should be several alarm conditions. If you have a machine on which some I/O functions operate (LED's, Relays, Switches, etc.) but others do not, either the I/O board is bad or there is a wiring problem in the wiring between the board and the devices. Also, be sure to check the power going to the I/O board, particularly the 24 volts at the six pin connector CDP.

Some inputs, such as Cycle Start, are not activated when their associated bit goes high but rather when it goes low after being high. That is, the address tied to the Cycle Start button is normally low or 0. When the Cycle Start button is pressed, it goes high or 1. If the button is pushed and held nothing happens. Only when the button is released and the bit goes low again does the cycle start. The importance of this is that if a machine executes a program on it's own without being commanded, it can't be caused by a Cycle Start button that is stuck, etc. You need to look either for an I/O problem which causes the signal to go high then low or for an internal control problem.

The cable pin outs for a DB-25 to DB-9 cable to perform DNC operation:

2 ------ 2
3 ------ 3
4 ------ 8
5 ------ 7
6 ------ 4
7 ------ 5
8 ----

If you get garbage on your PC when outputting parameters, etc., check the SETTING page to be sure that ISO = 1.

If a M, S, T alarm occurs on the CRT check the program to make sure there is not an M06 in it.

If a machine's controller shuts down at the end of a program or anytime M02 or M30 is executed, check the Auto Power Off function. This can be either a push button or it may be turned off and on through the Software Operators Panel. In some cases a Keep Relay may be assigned to this function.

In rare cases it is possible for all of the instructions on a rung to be satisfied but the output coil does not turn on because certain parameters have gotten scrambled. Typically, the ones scrambled will be those you cannot see so you might try clearing the memory then reloading the parameters. If you do not have a copy of the parameters you can backup the ones already in the controller and reload them by RS-232 or by typing them in. The mere act of clearing the memory may resolve the problem.

In order to communicate with a Fanuc controller via an RS-232 port the I/O Channel (Setting Page) must be set to either 0 or 1. Also make sure you are in MDI mode and that the Edit Key is on.

Baud Rate Settings:
1 =    50
2 =   100
3 =   110
4 =   150
5 =   200
6 =   300
7 =   600
8 =   1200
9 =   2400
10 = 4800
11 = 9600
12 = 19200

If the Relative position display zeros when the RESET button is pressed make sure the MAN/ABS button is in ABS.

For a controller that has board mounted ROM Never power the controller up with any of the ROM chips off of the board. Doing so will cause memory loss and scrambled memory. If this occurs, the memory must be cleared resulting in loss of parameters and programs. The same is true for replacing the memory back-up batteries. Control power must be on while batteries are being replaced.

The Macro Executor Cassette can write information to any part of the CRT. If you see data displayed which appears abnormal for a Fanuc controller you can try removing the cassette to see if the data is removed. One example is when OFST flashing and the Offset page being displayed on a lathe when the tool setter is down.

There is a strange condition that may arise if the program storage area becomes scrambled. On some machines if an ATC cycle (M06) is attempted, when the M6 is read in the ATC program, the controller will delete everything after the M6. This portion of the program will simply disappear. This condition has only been observed once to my knowledge and it was resolved by clearing the program storage area.

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Warning and Liability Disclaimer

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.