Created Date: July 03,2008

Created by: KPrice

mdangelewicz, since you are able to see indicator lights turn on and off correctly, I assume your communication settings are good. You 're using serial comm with K-seq, and you 're comm settings match? I'm thinking you 're C-more switches are not mapped correctly, your C-more switch should turn on and off a "C " bit, and that "C " bit should turn on and off in the PLC. Could your switch be momentary, or you have no latching in the PLC logic? If this is true, the "C " bit could turn on and off before the PLC, or you, has time to see it? Another thing to look for is that you do not have logic that resets the "C " bit that you are trying to turn on with the C-more switch. Hope this helps.

Created Date: July 03,2008

Created by: Steve Bailey

Basically what Kprice is saying is, don't try and control 'X ' bits from an HMI. It won't work. Use 'C ' bits instead.

I want to clarify what rlp122 said. You can have an HMI write to X bits, but you have to be careful when you do. If your PLC has an input module addressed to the same X bit that the HMI is trynig to write to, then the data from the input module will prevail. If there is no input module writing data to an X bit, then the HMI can write to it. The danger with doing that is that it might work fine for months or years, but if you later add an input module addressed to the same X bits that the HMI is using, your HMI will no longer work because the data from the input module will take precedence over anything from the HMI.

Created Date: July 03,2008

Created by: mdangelewicz

Thank you for the info.

My follow up question is, if an "X " input is controlled from a real world sensor and turns on "Y " which turns on a real world output, how is/does the Plc recognize a "C " input from the HMI to turn on the required "X " input ( which may also be turned on by a real world input) of the PLC. Am I correct to assume that the "X " and "C " are parallel inputs?

Also we have the users manuals, but are there any programming manuals or tutorials that are available.

Thanks again for your valiable input, much appreciated!!!

Created Date: July 03,2008

Created by: Steve Bailey

Am I correct to assume that the "X " and "C " are parallel inputs?

It's not automatic.

You have to think of the C bit that the HMI writes to as an independent input. If you had two start buttons hard wired to two separate X inputs, you would have to write ladder logic that OR'd the two inputs so that either button would make the machine start.

If you have a hard wired X input and a C bit from the HMI, you will have to write ladder logic to OR the two signals.

Created Date: July 03,2008

Created by: bcarlton

The OR of the two conditions, one from X inputs and one from a C bit controlled by the HMI, may need to be conditioned. If you want either condition being true to turn on the output then a simple OR (parallel) circuit is appropriate. But you may have another item, like an Auto/Manual status to be taken into acoount to decide which condition to follow. All this will have to be worked out in your ladder rungs for each PLC/HMI controlled output.

As far as learning PLC programming try the online tutorial at www.plcs.net

Created Date: July 03,2008

Created by: mdangelewicz

We are setting up a PLC lab and are having difficulty in the DO6 plc seeing inputs from the HMI panel. The panel will see the PLC input/output go true and turn on/ change the panel switch/light, but pressing the panel switch will not cause the plc to go true (respond). We have tried the slave/master thing but no help. we are using c-more software for th panel.

thanks for the help