Horner PLCs

[Clart]

We have a number of Horner PLCs on our production line. Recently they have started randomly dropping off the network. We setup constant pings to the PLCs and the PCs on the line – the PCs never drop out but once 1 horner goes, it seems to take out all the others. Pinging from the switch has the same result do I don’t think it’s the network or cabling.

Any ideas?

 

[*JimmyJ*]

Firewall's

 

[Clart]

not a chance

 

[sn00p]

Embedded TCP/IP stacks can be sods in systems with limited resources at the best of times. How often do they fall over?

We use an embedded TCP/IP stack and if we run out of RAM (I'm talking about devices here with 64 kilobytes of ram!) we lose the ability to receive packets but the devices can still send.

I'm guessing it's not that easy to stick a small hub and PC near one of these things to monitor the ethernet traffic to see if anything at all is happening (once they appear dead) or to try and nail down the cause of why they're failing?

 

[Clart]

they can be fine for a couple of hours, losing the odd ping here and there, then all of sudden, one will completely drop off the network for a couple of seconds, and come back. This then seems to trigger all ther others losing conectivity. It gets so back that we have to reboot them all, and the cycle repeats itself. Network traffic is barely touching 1% and they are all in the same switch, with all the patch leads replaced.

 

[sn00p]

If at all possible I'd definately try connecting one of the PLC's via a hub with a PC connected and set it capturing packets that are being received and transmitted by that PLC, at least if you're plugged into the network at the same termination point as the PLC you may be able to see what is happening, and at least verify that your pings are getting to that end of the network.

I guess on a production line this possibly isn't going to be the easiest thing in the world to do.

 

[KDF]

I concur with sn00p, that would be my action.. would give you much more information as to what is happening and what might be triggering the problem.

 

[Clart]

update - new PLC with updated firmware doesn't lose connectivity. However, the software our supplier wrote doesn't work on the new firmware yet. great!

 

[sn00p]

Oh dear!

I thought about suggesting updating the firmware on a unit earlier, but figured you may end up with a problem like that.

Hopefully it won't take your supplier long to fix, most likely they'll just need to recompile the logic with the latest tools.

Still, at least you've got to the bottom of the problem and a full fix shouldn't be long in the making.

 

[Lagerlout]

Stop using s**t PLC's?:clown: