AB SLC5/05 Commnunication Problem (PLC to PC)

[yuriyellat]

Hi.

PLC is SLC5/05
Connection to PC is Ethernet

Here is the problem. Our client has got AB SLC5/05.
PLC was running for several years (7 and more), but recently strange things started to happen: sometimes connection between PC and PLC is lost (PLC does not respond to ping requests). The FLT led is off, PLC is running, the whole plant is running, but no connection with PC. ENET led is always on (green, and is not flashing as ussual). May be once per minute ENET led flashes and reply on ping request is received.
When PLC is powered off/on then connection is up for a while and approx. 5% of ping request packets are lost.
I assume Ethernet on SLC is faulty...
I would like to hear your opnions.

Thank you

P.S.: I`m new to AB and SLC

[Ryzhij]

It seems you are right. However, I would start by replacing the power supply, because it is considerable 7 years of age.

[Kirillij]

yes, it looks like a problem with the physical state of the system. but it is possible that there is an error in the settings of network modules too(I have this happen when someone "intelligent" adjust the settings on your own or "improve existing equipment" without permission). any way first is - do like Ryzhij said.

[yuriyellat]

Thank you guys for your answers.
I`ve checked network settings and there was no network mask set (0.0.0.0). But PLC was working fine without the mask.
Anyway I`ll try to replace power supply and if this would not help, then I`ll replace PLC.

Thank you!

[samtenash]

I want to communication plc emulation with opc kepware.
can anyone help me ? please.

[rhddev]

Thank you guys for your answers.
I`ve checked network settings and there was no network mask set (0.0.0.0). But PLC was working fine without the mask.
Anyway I`ll try to replace power supply and if this would not help, then I`ll replace PLC.

Thank you!

With this mask your plc can access x.x.x.x full ip range, maybe the broadcast msg from bootp are taking too long to end and it increase unnecessary network traffic. Btw, network traffic should also be considered, I had many problems to communicate to plc through a router with high load level, the RSLogix could be very instable.

Exemple. PLC with IP 192.168.20.254 and mask 255.0.0.0 can access networks at 192.x.x.x; if possible change the mask to 255.255.255.0 to limit the network access to 192.168.20.x