Modbus TCP/IP or OPC connection
I have to decide which protocol shall I use for receiving and transfering small amount of data between ABB 800xa v5.1 system (domain, two redundant AS/CS, separated client/server and control network) and remote ICONICSS SCADA system with Hitachi PLC. Systems are not in the same network, but they will be connected through GSM router that will somehow have access to ABB network. Possibilities are:
1. Modbus TCP/IP connection (AC800M is master and two Hitachi PLC-s are slaves), over newly created MODBUS TCP/IP VLAN.
2. OPC connection (primary AS/CS is client to remote SCADA OPC server), or the other way arround - we'll have to choose. It is proposed that we should install the ICONICSS GenBroker software that creates communication tunnel so there should be no need for DCOM configuration.
Do you have any opinion, suggestions regarding this topics?
Thanks in advance,
Voted best answer
> "Systems are not in the same network, but they will be connected through GSM router that will somehow have access to ABB network."
Honestly, it sounds like it has the potential to be an unreliable piece of ****. So the fewer components that can break the better.
If you use OPC, you're going to need a tunneller of some kind and you'll have a bunch of software from different vendors running on top of a GSM link over a network that you dont have any control over. Everyone will blame everyone else when it goes wrong.
A direct PLC to PLC link using Modbus TCP/IP is about as simple as you can get, and the actual data transfer relies only on having a tcp link that you can send packets over. It doesnt rely on any windows boxes or software, Its likely to be the most reliable solution and most likely to recover whenever the link fails and has to restart itself. You dont even need to use the 800xA networks, just put it on its own VLAN and let the customer worry about the connection.
I've tested the proposed OPC connection between two virtual machine systems on Monday. I've installed the OPC tunneler on 800xA, and configured ABB, and I've recived their data through tunneler. Two more problems have to be solved (sending the AC800M data to other system and restricting visibility of 800xA tags).
The other bigger issue is that today I've turned on the test 800xA virtual machine, and somehow PG2 alarm objects were created in the Control structure (sending picture in the attachment). I suppose this is the problem Rob you were telling me about. :)