Hi,
I am having problem with communication via third-party Scada (Citect 7.10) to a 1761-Net-ENI, connected to a ML1200.
The Scada is running on a PC, linked to the Net-ENI, retrieving data directly to the PLC (with Citect's built-in A-B communication driver, using port 44818).
We tried 2 different method of communication:
1. Radio linked
2. Cellular linked, over internet
The problems observed were:
Loss of communication over time (1 day to 1 week) between scada and NET-ENI/PLC and...
* Net-ENI web page still available.
* RSLinx would not recognize unit (yellow "?" with a red cross)
* Ping could be done
* No apparent error (fault LED)
* PLC still worked fine (for controlling automation part)
* Only way to get comm back was to power up the whole unit (PLC and NET-ENI)
Some local A-B retailer told me that my problems could come from the fact that both of my link weren't completely "reserved" for the communication link (to be more clear, radio link had a camera also, PC, printer, etc., compared to a "reserved" link that would be PC <--> Comm cable <--> PLC only, no other network equipment, and internet linked was not protected with something like a VPN) (hope that was clear enough). That was due to the fact that NET-ENI had a limited amount of inc/outgoing connection (2 in, 2 out, 2 mixed) and that some network equipment would use those (like a camera or printer) and have my scada get a loss of communication over time.
I have 3 questions regarding that.
First...
What way could i setup that in order to have less problem on both of my communication method:
1. Radio-linked: Have a VLAN only for PLC and PC? Get all other network equipment out of that VLAN?
2. Cellular-linked: Have a VPN? Have a firewall restricting only some port and some IPs?
Second...
Is there any way i can have a clear diagnostic of what's happening when the Scada stops communicating? I have no error on NET-ENI, PLC do still works, web page is ok, just can't connect data to scada...
Third...
I heard, looking into various forum, that NET-ENI could have problem dropping connection that aren't active anymore. Like if my PC is having a communication glitch, the NET-ENI would then use a new connection and not drop the first one, so after 3 glitch it would loss communication. Could that be true?
Some more information:
* Scada's error is something like "Can't communicate, channel (I/O device) is disconnected"
* Testing my setup while it was working fine, i could have RSLinx, Remote PC with SCADA and a local laptop also with scada, all connected to PLC, all working fine. That was done with electrical and network failure simulation, rebooting, cable disconnecting, etc...
* I think my NET-ENI is a "D" revision, could get that confirmed if needed.
* My scada is polling data at a good rate (let's say something like once every second, for about 15 tags)
Besides my main questions, if anyone has any clue on what could be happening, please feel free to add replies!
Thanks a lot for looking into that,
JPS
PS: I do have searched on many forums, have found some similar problems but without clear answers, so if i missed one, will be happy to be redirected to it.
I am having problem with communication via third-party Scada (Citect 7.10) to a 1761-Net-ENI, connected to a ML1200.
The Scada is running on a PC, linked to the Net-ENI, retrieving data directly to the PLC (with Citect's built-in A-B communication driver, using port 44818).
We tried 2 different method of communication:
1. Radio linked
2. Cellular linked, over internet
The problems observed were:
Loss of communication over time (1 day to 1 week) between scada and NET-ENI/PLC and...
* Net-ENI web page still available.
* RSLinx would not recognize unit (yellow "?" with a red cross)
* Ping could be done
* No apparent error (fault LED)
* PLC still worked fine (for controlling automation part)
* Only way to get comm back was to power up the whole unit (PLC and NET-ENI)
Some local A-B retailer told me that my problems could come from the fact that both of my link weren't completely "reserved" for the communication link (to be more clear, radio link had a camera also, PC, printer, etc., compared to a "reserved" link that would be PC <--> Comm cable <--> PLC only, no other network equipment, and internet linked was not protected with something like a VPN) (hope that was clear enough). That was due to the fact that NET-ENI had a limited amount of inc/outgoing connection (2 in, 2 out, 2 mixed) and that some network equipment would use those (like a camera or printer) and have my scada get a loss of communication over time.
I have 3 questions regarding that.
First...
What way could i setup that in order to have less problem on both of my communication method:
1. Radio-linked: Have a VLAN only for PLC and PC? Get all other network equipment out of that VLAN?
2. Cellular-linked: Have a VPN? Have a firewall restricting only some port and some IPs?
Second...
Is there any way i can have a clear diagnostic of what's happening when the Scada stops communicating? I have no error on NET-ENI, PLC do still works, web page is ok, just can't connect data to scada...
Third...
I heard, looking into various forum, that NET-ENI could have problem dropping connection that aren't active anymore. Like if my PC is having a communication glitch, the NET-ENI would then use a new connection and not drop the first one, so after 3 glitch it would loss communication. Could that be true?
Some more information:
* Scada's error is something like "Can't communicate, channel (I/O device) is disconnected"
* Testing my setup while it was working fine, i could have RSLinx, Remote PC with SCADA and a local laptop also with scada, all connected to PLC, all working fine. That was done with electrical and network failure simulation, rebooting, cable disconnecting, etc...
* I think my NET-ENI is a "D" revision, could get that confirmed if needed.
* My scada is polling data at a good rate (let's say something like once every second, for about 15 tags)
Besides my main questions, if anyone has any clue on what could be happening, please feel free to add replies!
Thanks a lot for looking into that,
JPS
PS: I do have searched on many forums, have found some similar problems but without clear answers, so if i missed one, will be happy to be redirected to it.