MD-HMI issue

[cch1955]

I while back I asked about the correct key routine for my hardware( FMD1616-10, MDEXP1616R and MD-HMI)
I implimented what you suggested and it works - pretty well.

The problem is that if you hit or hold the key it will often change the displayed active input key from the correct key to one above or below the correct key. So if I press the 5 key when I am watching online on PC input for a second the 5 key may go on, then change to a 4 and then go back to a 5. All 0-9 Backspace do this. Seems like a scan-debounce issue to me.

I have tried various scan rates for the routine and checked it against other Triangle machines I have programed here, no help.

Suggestions?

 

[cch1955]

More inforamtion. I swapped the MD-HMI out with another I had and the problem went away. Further investigation was that the cables were picking up noise from a AC servo drive cable. I rerouted the cables and the problem was gone from the original unit.

[support]

Thank you for your clarification. Did you also extend the MD-HMI cable beyond its standard length of 3 ft? Longer cable also tend to pick up noise and beyond a certain length the signal propagation delay can cause trouble. MD-HMI is not designed to be placed far away from the CPU (RS485 based HMI such as the touch panel would be much better).