I'm just go to troubleshoot some old PLC Siemens S5 , the CPU is S5-135U and there's a CP524 communicate with a computer using Wonderware for its SCADA system.
The first problem is the CPU doesn't want to run. There are fault leds lit QVZ, IS1, and IS2. I try to read the program directly to the CPU, but it can't be done. So we try to change the CPU with a new one, same type but new version. The old version uses 2 slots, but the new version only uses one slot. We copy the program from the EPROM with a PG and then downloaded the program to the new CPU, but we don't use EPROM for the new CPU. The manual says the CPU can run without EPROM, because there's RAM memory in it.
The second problem is we are trying to run the new CPU but it was so hard to run, sometimes the STOP LED flashing slow when we change the switch to RUN. We must change the switch several times then the RUN LED lit. My senior said that it was caused by the startup programs OB21 and OB22, but I still don't know what really cause it. Is the startup sometimes fail?
The third problem is the Wonderware doesn't communicate with the PLC. I never use a Wonderware so I don't know how to set the communication interface between the PLC S5 and the Wonderware. There's a program to link between the PLC and Wonderware, I forgot the name but this program could set the baud rate of the port used. We set COM1 with baud rate 19200kbps, the program shows texts R and W, I suppose this Read and Write. And right next to it are the memory addresses used. And after that was there are text DUE, I don't know what that mean. All the R are DUE, but the W not. What is this mean, does all must DUE to communicate or not DUE?
