Problem with updating clock in A/B PLC-5/30

[chipmoseley]

I am trying to dynamically update the running PLC clock in a A/B PLC-5/30 to keep it synched with a controlling time from a master computer. I have the same program running in three different PLC5's but the clock only updates in two of the PLC's. When I move values into S:18 thru S:23, the clock does not actually change. Does anyone know anything that will prevent the clock from updating?

 

[Mickey]

Something else writing to those registers? HMI?

 

[Donnchadh]

Hi

I am with Mickey or maybe another plc or scada

Donnchadh

 

[Bit_Bucket_07]

I've never had a problem setting the time in a PLC-5, but you might want to look at Properties for your S2 data file on that particular processor and verify that the file is not write protected.

 

[chipmoseley]

Something else writing to those registers? HMI?

Good thought. Nothing else on line (or connected) with this processor. Processor was isolated to a stand-alone condition. The "move" seems like it functions but there is no visible data change in the clock.

 

[Mickey]

Good thought. Nothing else on line (or connected) with this processor. Processor was isolated to a stand-alone condition. The "move" seems like it functions but there is no visible data change in the clock.

Can you post the program? Its .RSP file, zip it first.

 

[chipmoseley]

I've never had a problem setting the time in a PLC-5, but you might want to look at Properties for your S2 data file on that particular processor and verify that the file is not write protected.

Yeah. That is what I am thinking too. I have checked the normal data table write protection. I have checked S:2/15 and S:26/6 and they are clear. Not sure what other protection there might be to data table write or Status File writes.

 

[Bit_Bucket_07]

Yeah. That is what I am thinking too. I have checked the normal data table write protection. I have checked S:2/15 and S:26/6 and they are clear. Not sure what other protection there might be to data table write or Status File writes.

If you want to attempt a brute force patch, then try writing your time data to words in a different Integer Data File and then move that data to the System clock words in your PLC program logic.

 

[chipmoseley]

If you want to attempt a brute force patch, then try writing your time data to words in a different Integer Data File and then move that data to the System clock words in your PLC program logic.

Yup, that is exactly what I am trying to do. The data transfer seems to work (and it does work on my other processors) it just doesn't record. Feels like it is being access blocked but I can't find any block.

 

[PLC Pie Guy]

Hey there.
Have you actually cross referenced the bits S:2/15 and S:26/6 to make sure there is nothing in your program writing to those addresses. It does not have to be another device over writing the addresses but something in your own logic.

Juat a suggestion!

 

[chipmoseley]

Good suggestion. Nothing there though. :-(

 

[Bit_Bucket_07]

I have no real reason to believe that it is even relevant, but I wonder if this particular processor is of a much older revision than are your others?

 

[chipmoseley]

Can you post the program? Its .RSP file, zip it first.

I can't post the whole program - against company policy. Here is the rung responsible to perform the update (also, archives the update for later review).

 

[chipmoseley]

I have no real reason to believe that it is even relevant, but I wonder if this particular processor is of a much older revision than are your others?

Good question. The processor in question is an older revision that the ones I have working. Worth some review with Rockwell.