OMRON touchscreen

[Skidog 0]

I'm using several of the 620s and having trouble with one, it loses connection to the host randomly. What I saw first was a connection loss whenever an estop condition was initiated, started tracking that through the logic. It was then reported to me that it happened randomly and got me thinking I was barking up the wrong tree. First thing I replaced was the NT-AL001 232-422 interface, nope, replaced the touchscreen itself, nope, finally replaced the PLC CPU and P/S, nope. P/S for the touchscreen was checked and rock steady at 24.02 VDC. Any ideas or suggestions would be appreciated. The only thing I haven't changed is the seriel cable which runs between the adapter and the PLC, it's located in a cable tray in the basement and not subjected to any movement, that's why I haven't changed it. The ends look ok, no damage there. I plan to set up the components I removed on the bench tonight and see how they work together outside the equipment.

[Jay Anthony 118]

In response to your issue, Here's a chain of email that I conducted with rhorton: It could be the cable. Try automatic rest.

[Guest rhorton]

Ended up being a flaky plc power supply that was causing my problem

[Skidog 0]

OK, I checked and auto reset is on. When it drops out I get 2 messages, one is 'connecting to host' and the other is 'setting memory'. I have not noticed the comm or power lamp flickering. I'll continue reading the manual and tinkering tonight until 5am, and promise to post results here. I may even break out the o'scope and check the P/S for AC ripple, which is easier than replacing it. I know it's going to be something simple in the end, don't want to overlook anything.

[Jay Anthony 118]

IMHO,'connecting to host' is an intermittent cable. I haven't ever seen a 'setting memory'.

[Guest Guest_bigdog]

try replacing the cable with a shielded cable, and in some cases, I have had to install line filters on the incoming ac power as well as to the output of the dc power supply. Lots of harmonics when measuered with a scope if servo drives or ac inverters are mounted inside same cabinet as the plc. Have only had to install the extra line filters on machinery that have servo motors and amplifiers inside the same cabinet

[Guest Gili]

I would like to add another possibility for the interference issue. It can also happen from dirty display power supply. Drops and spikes might cause communication problems and more. In several cases I found that the best power supply was a simple analog supply with no regulation (transfomer,bridge,capacitor). The internal display power supply can handle voltage changes from 18 to 32 volts. This power supply will be galvanically isolated from control voltage, and its cheap. Gili

[Skidog 0]

I'm still working on this, the screen stays on as long as there is no estop. Once machine control reset is lost it displays connecting to host until reset is restored. I'm scheduled for the class in November but I hear that class doesn't deal with this model! Ah well, I'll keep after it, and post my findings.

[Jay Anthony 118]

How about the 5VDC power supply for the NT-AL001? Is it connected through the e-stop?

[Skidog 0]

PS to the NT-AL001 was OK, changed the PLC rack P/S and CPU, problem cleared. Now I have a new problem, I can't change the CPU node from 0 to 2. I know it can be done and I'll keep after it until I figure it out tonight. My memory isn't what it used to be I suppose, and my notes from CS1G class don't help me either. I ran into the same problem there and Jay showed us Omron noobs the way. More to come.

[Jay Anthony 118]

By now, you probably have found it. It's under PLC settings - Hostlink port:

[Skidog 0]

Yeah that's where it was alright, but I was already using that. The problem was that after I changed it I could not get back online. Eventually I did get back online after changing the node ID but I'm not sure how. I will try to recreate the problem tonight, if time allows, using our training simulator. I put the PS back in and the touchscreen problem did not return. Bad host link port. The last time I worked on this equipment I was led astray into thinking the CPU was in cabinet 1 when in reality the CPU was located in cabinet 2. I'm new in this department, still having to take peoples word for things. Thanks for all your help.