PLC Outputs - Module Issue

Hi Paramasivan4u,

Siemens Simatic S5 PLC?

I'm profiling, since outside the U.S., Siemens used to be the big global PLC player (around 2001 - vs. Allen-Bradley), and I think may still have a bigger global market share than Rockwell Automation.

- Larry

Hi there,

If you have to re-cycle the power on your PLC, especialy Siemens S5, then it sounds as if it a software issue.

You will need the Com software to check the setup of the PLC i.e. does it retain flags and that sort of thing. You will also need to check the user program, as it sounds as if there is something that is being retained, again I would guess a flag, but might be in a DB.

Good luck.

Craig

Paramasivan4u,

Frequently, the I/O module needs to be powered on before the CPU, so the CPU will recognize its presence and properly address it. I have had this problem with Siemens analog modules in a remote I/O rack. The symptoms you state sound like this.

With some modules, the program has to write configuration data to the module. In this case, you can possibly use a time delay based on the first pass bit, to wait a second or so before writing this configuration data. If all else fails, you may have to find a way to get the rack powered before the CPU.

Troubleshooting can lead to the engineer's version of "male pattern baldness", with hair being pulled out in clumps! However, persevere, and I believe you will find and fix it.

Regards--JMM