Author Topic: Modbus TCP  (Read 1922 times)

gomond

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Modbus TCP
« on: June 04, 2014, 06:25:20 AM »
Hi Archie
I am a total newbie and just getting my head around this stuff.
I have been using a modbus client (comtest pro from baseblock, awesome) and I can read the meter by setting it to unit address 1, function 3 and read address 0x5000 and it returns a bundle of numbers representing the current energy consumed in kWh.

In advanced HMI I have set the modbus connector to the IP address  192.x.x.x, unit id 1 but I dont know what to put in the PLCaddressxxx fields on the meter objects and the like.

I am enjoying the learning process, though I feel pretty dumb at present.
A modbus video would be awesome..

Thanks.
« Last Edit: July 02, 2014, 01:44:16 AM by gomond »

gomond

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Re: Modbus TCP
« Reply #1 on: June 04, 2014, 11:55:03 PM »
Would I be correct if I assumed that the PLC address field should contain 320480 to read holding register 0x5000 (20480 dec) ?

I am also assuming that the unit id on the ModbusTcpCom is the remote device ID (like rtu/485).
so does this mean that for every device on  the 485 bus via the transparent converter a separate instance of ModbusTcpCom would need to be created.

Cheers.
« Last Edit: July 02, 2014, 01:44:35 AM by gomond »

gomond

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Re: Modbus TCP
« Reply #2 on: June 05, 2014, 03:17:29 AM »
I just got home and tried the above and it returned INVALID VALUE RETURNED "Illegal modbus function".
So I I guess that is not the answer.
« Last Edit: July 02, 2014, 01:44:59 AM by gomond »