PLC5-40

[Guest val]

Hi Helpers, I have an intermittent problem with an Allen Bradley PLC 5-40 processor faulting out and going to the default program which has no ladder logic. We keep having to load the program everytime this occurs! Our setup does contain a remote I/O rack. In talking with Allen Bradley their suggestion is to change boards out. So far I have changed out a processor board and an Analog Input board with no luck. Anyone have any suggestions/solutions? Val

[Gerry 13]

...in other words, the memory is being cleared. Maybe the battery is dead and the mains supply is being interrupted.

[Guest Mickey]

I had same problem a couple of years ago. Installing UPS to condition power seem to cure problem. At least it has not reccured.

[Guest Guest]

I have had this problem with a 5/80E processor. The PLC would do a "Hard Fault" which would cause the processor to lose the memory [occured every 3-5hrs] - have to start from scratch everytime. The problem was occuring from the communication through the ethernet port - AB was not sure to the "exact" problem but was aware of it. They ended up sending a tech out - no help [but no cost either]. Allen Bradley does have a program that does suck the brains out of the processor to try trouble-shoot the reason for the last hard fault [with the help of AB]. The program is called "IBDEAD", the file it produces is then meant to be sent to AB for further dicing and slicing. If you continue to have problems, this might help... it just reconfirmed our problem, and helped confuse them even more. During our trouble-shooting, we replaced racks, power supplies, added filters, reduced "excesive" code... all to no avail. What solved our problem is when we replaced the ethernet hub [we tried several brands in our troubleshooting] to an ethernet switch. The system had been running fine for about 2 years before the big hickup... so what chaged? As to your specific problem, it is going to be really hit or miss. Allen-Bradley tech support can be very good [if you end up talking to the right person], but it unfortunaltly is up to you to solve the problem [life of an enginerd]. I would consider looking at power [brown outs] & communications issues first. You may also be overloading the power supply, for example the P7 [biggest power supply for AB] cannot handle 16 analog output cards [if you stay within the printed amp rating].

[Guest Alan]

You could put a memory card in and set it up to auto load the program when power is cycled to the PLC. I had a problem like this and the cause ended being field mice making a home in the power supply it shorted out the system when we got to it (it was in a remote area and took some time to get to) it would fire up again and reload the program and run for some time until the mice pidled in the power supply again. Problem was solved by filling the small gap around the power supply and blocking the holes to the cabinet.

[Guest PLC5PRO]

What is the processor fault? Also check the battery and if that does not work add a UPS. I would advise installing a EEPROM and burn the program in. Are you using a STI subroutine? If so you might want to consider using a UID and UIE to prevent STI overlaps.