Communication or Application

[mkees]

I am working on an emissions monitoring system (Manufactured by Systems Monitoring). We had a thunder storm come through the area and is the possible blame for my problem. The NOx analyzer had to be sent out for repair, no big deal. But with the rental unit installed I tried to perform a calibration sequence, this didn't work. I was able to calibrate the analyzer but connecting the zero and span gases directly to the analyzer. With further investagation, I discovered that the control system is just an HMI (called CEMDAS) communicating RS232 converted to RS485 (this is a B&B electronics converter) to a GE Fanuc 90-30 plc. I am not familiar with this plc but it seems that the program is not running, and I can not get on line with it to see if it is running. The lighted indicators on the plc power supply show it is running, and there are 2 lights P1 and P2, P1 is lighted. I have checked as best I can with the HMI seems as though it is working, although I can't find the HMI server to check. I have not been able to talk to the manufacturer, they won't return my calls. Anyone have any ideas on what else I can check? How to check communications? or how to get online with the plc (I have the software but not the program)? I have also tried a new RS232/RS485 with no success.

 

[dV8r]

The P1 LED indicates taht you have communications being attempted on port #1 of the PLC. Have you tried cycling power on any of the components, PLC, RS-232 to RS-485 adaptor or the HMI?
In my experience if the P1 LED is on constantly there is a problem with the Mater device, that is generally the HMI.
The P1 LED should flash on only while datat is being passed between the PLC and HMI.
If the Run LED is *on* the PLC program is running you can depend on that.
Sometimes just un-plugging and re-plugging the comms cable will restart the link. It can't make it worse.

 

[djs]

Also on the CPU of the 90-30 there should be a key switch. Using this you can try to place the PLC into run mode.

 

[mkees]

Thanks for the information, I did cycle power on both the plc and the hmi, but no help. The manufacturer did finally call back and found that a DCE application was locked, they stopped and restarted it. One would think that if you reboot the computer the hmi is running on that that application would restart, and earlier when I went to Task Manager that application said it was running, weird software. Regardless the manufacturer did something and it's working now.

 

[JBinCA]

In regard to DJS's comment, not all GE 90/30 PLCs have CPU modules, some have the CPU embedded in the backplane. The backplane CPU models do not have the keyswitch.

The power supply module should have three green lights on it: PWR; OK; and Run. If the run light is on, the code is running.

It sounds as if your problem was just with the comms though.

Regards,

JB