Dear Forum;
I have a DIGI IAP which gives ethernet capability to one serial device. We set a “printer profile” in the DIGI and our application support ethernet encapsulation so we didn’t nee to configure any RealPort (virtual serial COM) in the computer.
Now we want ot give redundancy capability to our appliocation by setting a second computer with the same application so both computers will request data simultaneously to teh serial device…is it possible?
Perhaps - can you describe the protocol used?
If it is a pure half-duplex (PC requests, device answers) then the DOIAP has an Industrial protocol called ‘custom’ which allows the DOIAP to act a bit like a print-server, so it interleaves transactions for more than one “master” to one serial slave.
However, it cannot handle protocol where the slave doesn’t answer some requests, may return more than one response and so on.
Thx for your post. You could find the protocol details in attachment
Dear M Lynn
When DIGI is set as Printer and both servers trying to poll data…only one is able to do it. That’s OK for us.
When I disconnect on purpose the network cable in the primary server, the secondary server (running the same application) doesn’t start polling data.
DIGI support tell me something about TCP socket…now my question:
How to close the socket in a DIGI when a server shutdowns to allow the secondary server to take that socket?
Regards
You probably need to set the TCP Keepalive to a small value (like 30 seconds). The problem with TCP is it can take “time” for one end to decide the other has ungracefully gone away. a 30 second Keepalive means the Digi would “demand” the remote talk TCP packets (with or without data) every 30 seconds.
I explain it here:
http://digitips.wikispaces.com/PS3_Enabling_TCP_Keepalive
I looked at your protocol, the details weren’t full but the IA Custom protocol might work.
Give the TCP Keepalive a try … plus from the Web UI you can manually “kick out” a connected host - see the “Management - Connections” link.