[malaron]

Hi everyone,

We recently changed our memory board for a rebuild one and have the following problem now:
We can send programs from a PC to the machine without problem but we cannot send anything from the machine to the PC. We have tried with both ports (M5 and M74) and have the following results:
M5: No transmission machine-PC whatsoever. The machine can receive OK with the PC set to "No Flowcontrol" (So the XOn/XOff are not working).
M74: We have transmission machine-PC but its all junk and not ASCII. The XOn/XOff work fine as we can even use the drip feed from the PC to the machine without any problems.
We have tried all baud rates and even baud rate mismatches but have no success. We have tried 1 and 2 stop bits. We have tried configuring the ports as "RS232" and as "New interface" as well as the ISO/ASCII parameter and the result is always the same PC-machine works machine-PC gives out junk (and nothing at all in port M5).
We have done trials with short cables directly to the ports and have no difference. We have used several computers with no success. We even checked the signal on en O-scope. M74 has a good signal level M5 has nothing.

Are we missing something (a parameter perhaps)?? Is it possible that one side of the RS232 is damaged and the other one OK?

Thanks for your help.

Michael

[Dan Fritz]

When using the M5 plug, your Fanuc cannot send anything. This tells me that the Fanuc control does not see the "CTS" (Clear to Send) signal on pin #5 of the Fanuc plug. If your cable has pin 5 on the Fanuc wired to the PC side, or if your cable has a jumper between pins 4 and 5 on the Fanuc side, then the Fanuc SHOULD be able to send. If, however, you have a blown receiver IC chip on the Fanuc board, then it will not be able to see the CTS signal no matter how your cable is wired. The solution is to repair the main board by replacing the 1489/75198 chip that is responsible for this signal. If the CTS signal is not visible to the control, it will ATTEMPT to send, but it will not be able to. The EDIT symbol will blink forever and you'll have to press RESET to stop it.

When using the port on the M74 plug, you obviously don't have a bad IC on the CTS signal (it's a different IC on the board), so the control can send and receive. Your problem there is not the baudrate or stop-bits, otherwise you would not be able to send data to the CNC at all. I suspect that the bit marked "ISO" on your first parameter page is not set correctly. This bit (on some Fanucs called "PUNCH CODE") sets whether the control transmits ISO (the subset of ASCII) or the old EIA code, which your DNC software probably does not understand. Verify that this bit is set for ISO operation, then try to send the file again to your PC.

[GPena]

If ISO=1 then the memory board or the com port at your PC are damaged, replace the PC for anotehr unit and retry, if the pboblem remains then change the MEM board ifpossible and test.

Greg.

[malaron]

Thanks with the tip of the ISO parameter. Port 2 works. Port 1 still sends nothing, but the transmission stops as if everything was normal. Can the transmit channel be phisically damaged and the receive be OK? A computer guy told me that this is very very unlikely (not to say impossible). As I mentioned we have tried with 3 different computers.

Cheers,
Michael

[Dan Fritz]

It's certainly possible that you have a blown IC on the transmit line (pin 2), but the receiver on pin 3 is OK. Most Fanuc models have a 75188 (or 1488) driver IC for the output signals on pins 2, 4, and 20, and a 75189 (or 1489) receiver IC for the inputs on pins 3, 5, 6, and 8.

Just because one IC blows doesn't mean the other goes too. You can spot these ICs because they are near the M5 and M74 plugs on the main board. Replacing them on a Fanuc 0 requires some experience with removing and soldering IC to a 4-layer board. Don't try this if you've never done it before. It's just too easy to damage the board if you don't do it very carefully.