Bradley Smoker PLC-5 user manual Troubleshooting Remote I/O Communication Difficulties

6-12Communicating with Remote I/O

Troubleshooting Remote I/O Communication Difficulties

Follow these steps to make sure the controller can communicate with devices on remote I/O links.

1.Put the controller in program mode. Go into the memory map and find two unused file numbers. The controller will use these files. Do not create the files, just record which file numbers you will use.

2.Go to the controller status screen and make sure all rack inhibit bits are zeroed (0).

3.Go to the controller configuration screen and assign one of the previous file numbers to be the I/O status file (see page 6-7).

4.Go to the channel configuration screen for the appropriate channel and assign the remaining file number (from above) to be the channel diagnostic file (see page 6-7).

5.Perform an autoconfigure and confirm that all the racks were found and listed in the I/O scan list.

6.Check all I/O rack retry counters in channel status to make sure there are no communications problems.

If you follow the above steps and there are still remote I/O communications problems, it is possible that the I/O status file is corrupt. Try assigning a brand new I/O status file and repeat the steps above. Also, confirm that the I/O image tables exist for the racks you are having difficulty communicating with.

Publication 1785-UM012D-EN-P - July 2005