CJ1M PLC online problems

[raviiyer 0]

Hi, I am a rookie PLC programmer. I am having a strange problem with CJ1M. It has already a working program and controlling few outputs and VSDs (OMRON 3J3 JV). Recently I had to go on-line and make some changes, but could not do so. Following are the details. I use a IBM think pad - lap top, Windows 2000 and CX-Programmer version 5. I have the connecting cable and the plug for the peripheral port. Few days back I was able to get on-line and down load the program in the PLC! With the same set up I could not get on-line next day. PLC set up is correct CJ1M - CPU12, comms is set for 'Tool bus' and baud rate 9600, com1 and also the 'auto baud rate detect' is ticked. The whole set up of lap top, software and the comms cable is working for other OMRON PLCs. (Even it worked once for this PLC) There is one difference when I was able to get on-line. The plant controlled by this PLC was not running. While the plant is running, I am not able to get on-line. The program inside is quite simple doesn't change any port settings or anything, while running. OMRON tech support suggested, static may be a problem and asked me to try with earthing strap - the one used for cmos comonents. But it didn't solve the problem. When I am not able to go-online, the comms LED at the CPU blinks little dull few times and gives up, the CX-programmer comes up with a window, can't connect to the PLC. I tried the 'auto on-line' it didn't work either. Any ideas? Thanks Ravi

[Sleepy Wombat 27]

Is your programming cable shield connected at one end, You did mention VSD's were in the same cabinet, how close is your programming cable, computer to these drives when programming. Are the drives ustilising the same power supply as the PLC, are there filters on the power supplt to the PLC, do the VSD have filters ? I would suspect radio interference EMF from the VSD's.

[PdL 71]

Experienced this also once -the communications beeing disturbed by interference from the drives in the panel. Had to tie up my programming cable in the air ike christmas lighting

[BobB 58]

Can you still get online to the PLC when the machine is running? If not, you may have blown the serial port IC. I had 2 CJ1M processors sent bach to Japan for repair just recently. Serial port IC had failed.

[AC DC 0]

Switch off the VSD's and see if you can get communication. Otherwise try to use the RS232 port with a "Home" made cable.