Ge Fanuc Genius Bus Diagnostics

Hello all, first time post, although this site has saved me many times cheers!

OK... my problem.

On site we have a GE 90-30 with 364CPU and a BEM331 Genius Bus Controller. This is connected to 2 VersaMax NIU's. There is one output card on each NIU, and they both randomly drop out for 1-5ms(plus some scan time I guess). No faults are logged in either fault table and I'm monitoring the GBC and NIU 'status bits' and they never go offline.

The Genius bus is under 2000ft, baud rate set at 153.6e on all devices. The cable is Belden Profibus 3079A (hope this isn't an issue) Using 150 ohm terminating resistors. All earthing and screens have been double checked. Been through all of GE's fault finding tips with no resolution to the issue.

Have installed the latest firmware on the CPU364, the BEM311 and NIU's are the latest revisions.

Now I'm trying to write some code to the GBC to read it's diagnostics. I'm getting a relpy from the COMMREQ '8 - Command terminated due to syntax error' and '210 - Command specified is not valid for GBC'. I've tried different commands and I get the same reply. I address it to the NIU and it times out.

I'm stuck, can anyone help?

Cheers, Alex.

Hi Alex,

I don't have had this problems with a 90-30 system, but i had something like that recently with a Horner Genius interface.
It sometimes lost I/O communication for 1 or 2 bus scans, ( if it is more than 3 scans, then the bus would get down). It was indicated by the COMM_OK led on the bus controller, no errors reported to the PLC.
Normally it is on continuously, but now it turned off sometimes for a moment.
This was coursed by cabling problems.

You used Profibus cable, that is not recommended for Genius bus usage.
Profibus is electrical a RS485 system, means that voltages are low.
Genius bus works with much higher voltages, so the first thing I recommend is, use recommended cabling.
Use Belden 9182 (max 2000ft) or Belden 89182.
Both type of cables are to be terminated with 150 Ohms

Succes

gr. John

John.S said:

Hi Alex,

I don't have had this problems with a 90-30 system, but i had something like that recently with a Horner Genius interface.
It sometimes lost I/O communication for 1 or 2 bus scans, ( if it is more than 3 scans, then the bus would get down). It was indicated by the COMM_OK led on the bus controller, no errors reported to the PLC.
Normally it is on continuously, but now it turned off sometimes for a moment.
This was coursed by cabling problems.

You used Profibus cable, that is not recommended for Genius bus usage.
Profibus is electrical a RS485 system, means that voltages are low.
Genius bus works with much higher voltages, so the first thing I recommend is, use recommended cabling.
Use Belden 9182 (max 2000ft) or Belden 89182.
Both type of cables are to be terminated with 150 Ohms

Succes

gr. John

Click to expand...

I agree, when having problems with a Genius bus always start with the cabling and get it right first. The only alternative I've found adequate is to use AB Blue-hose if you can't get the GE Specified cable. And triple check your "shield in - shield out" connections.

You will be better served for the future by updating this system to PAC using Ethernet instead of Genius.

And the PROPER terminating resistor on the end of the line...(also see GeniusCable.pdf from RussB post #3).