Redlion DatastationPlus (DSPLE)

[amigo]

ok, I have configured DSPLE to have ModbusRTU slave on its rs485 port, Modbus TCP slave and BACnet/IP slave on its ethernet port.
I am passing some data between all the slave ports, no problems.
Now, I use one client software to monitor all three ports, Modbus RTU is solid, BACNet/IP is solid, but Modbus TCP keeps dropping in and out.

Is there something funky about DSP's modbus TCP slave driver and tcp socket closures? It looks as if once in a while when I write or read from that TCP port DSP shuts the TCP socket down and reopens it later.
As I said, BACnet/IP coming out of same ethernet jack is sold.

any ideas?

thanks.

 

[SteveMaves]

Don't suppose you'd have a Wireshark capture you could post? It's possible the connection is being reset by either the Master or the Slave device, and Wireshark would show us which one.

 

[DanYost]

Agreed, a traffic capture would help us determine why the socket is closing. I am not sure why the socket would be closing at all, unless something was telling us to close it.

Regards,
Dan

 

[amigo]

ok, thanks.
I will try to get a capture and post it here.

 

[mark73165]

Hello, I had the same problem using Modbus TCP but it was not the Data Station. Make sure your client program is not trying to ping a holding register. Once I turned this off then it worked fine. Also make sure the number of registers polled is the same as the number of registers in the Data Station.

I have also had to turn off the ping holding registers selection in the G310 displays using Modbus RTU when you are not polling a holding register, it seems to get confused when there are no 40000 registers on the other end. Thanks Mark

 

[amigo]

Ok, thanks.
I will also look at this ping thing you mention but don't quite understand what it does?
I mean, you just read and write registers. what purpose does this ping serve?
Is it just reading a register continuously to make sure the remote device is online?

 

[DanYost]

The ping is something we use to quickly detect an online device. We issue a single register read for whatever holding register is defined as the Ping Holding Register. However, this is only used when we are a master, so unless the Modbus TCP/IP master is another one of devices, it is more than likely not an issue.

Regards,
Dan