Unitronics & Modbus UDP

AJW

Member
Join Date
Sep 2004
Posts
27
Hey I am new member to this site.

This may be a repeat of a post I sent yesterday, but was unsure
if it made it on to the board. Any way here it is again:

The system is 4 Unitronics V280's 3 are slaves, 1 is the master.
I have talking and sending data between them. This is setup using the
MODBUS UPD over IP just like it shows in the examples.

The problem is, if 1 of slaves goes off line the comminications between the other units stop. I have read the help screens and found this is correct. I have added some handshaking between the units to indicated the communication status between the units and to take the apporate action. This is how I found the
problem.

However this is not what I need. I need the others to continue
sending data. I do not need the other machines(the slaves) to
stop if one is taken out of production.

Can any of you dig into your little bag of tricks and help me
with a work around?? Or am i just stuck due to the nature of this
beast.

According to the help screens the Unitroincs will use MODBUS TCP
over IP, but according to the examples thsi requires a lot of
additional code. It's not desirable but it might be my only
solution.

Let me know your thoughs.

Thanks

AJW
 
Did you ever get Unitronics to work with UDP modbus?

I am doing something very similar now.

It almost works, but not quite.
 
Hi guys,

I've only worked with modbus tcp, not udp, and I'm not familiar with the capabilities of that particular flavor of the protocol. I would try TCP and assign separate sockets to each of the units in question and see if that resolves it.

I don't know if you are "too far down the road to change course", but the V280 has a built-in Canbus port, which can do UniCan protocol between the controllers. It's a multi-master protocol based on CAN (sends only) and in the past I've removed units from the network without affecting the rest of them at all.

It's very simple to wire and extremely easy to program, and you can take units on and off the network all day long without any issue. It would also free your ethernet port up for other things.

Something to consider, especially if you're not using the Canbus port for anything else.

Best of Luck,

TM
 
This was a while back, and yes I did get it to but I do not have access to the software. What I do know is this is master slave and very liminted at that. The master must handle all the comms. I had 3 slaves and 1 master. If slave 1 wanted to talk to slave 2 then master had to the polling and be the traffic cop as well. So if the master went down then all bets we off. If Tim say CAN Bus works then I would try that. It's got to be eaiser. I don't not have any units to test with. I do know the local rep in NC who has done this recently.

Sorry I could be of more help.
 

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