DH+ Communication Problem

Hi all,

I had a communication problem that using 1747 l542c CPU and DH+ communicate from main panel to remote panels. What happened was that the control block in message function was stay solid sometime and make the communication drops, but if I toggle that block, all robots and machines back to running without a problem. I am wondering what cause this problem? And is there a way to automatically toggle this block when it stays solid after a few seconds? I am thinking about using a timer and one shot... but not sure if that will work.

Thanks!

When you have an on off transition on the input rung the message command is triggered. If it triggered again before it receives the done signal it can cause errors.
A common practice among programmers is to have data copied over occasionally based on a timer. I have done this when I wanted a periodic update. It does lack a layer of robustness that could get you out of trouble.

If all that is taken care of already then the next step is to look at the log of the communication errors. I've had this suggested to me but I solved my communication problems before I had the opportunity to learn how to do that. See chapter 13, 'SLC communication channels', in the instruction set reference and you will learn how to do this.

Hope this helped,

Glen

I have done a few projects that I would write the data to the other device (CPU and HMI) on data change... so it would not do anything until the data has changed, I dont like a lot of nothing on the network, you may want to look and see if they have done something like this but its not working very well

Thank you very much for your replies!