Q3065 I can read the data from an Allen Bradley SLC505 but I cannot write to it. Why?

Summary:

I have a test project in Citect connected to an Allen Bradley SLC505 via TCP/IP.

The communications interface looks to be configured ok.

If I set a bit in the PLC from the programming interface Citect immediately displays its value.

In the kernel you can see a steady increase in the comms error count as you try to write to the PLC from Citect.

What is the problem?

Solution:

The communications configuration in Citect looks correct. (In fact it is.)

Within the SLC505 setup there is the facility to "Write Protect" a communications channel.

This is set once only on setup of the PLC and once set will prevent Citect writing to the PLC via the comms channel.

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