M340/M580 reading Input Registers / Coils / Contacts (1, 10001, 30001 etc) using DTM Browser configuration

[BevanWeiss]

Hi all,

We've recently tried to use the DTM Browser to communicate with a ModbusTCP device which has data available for reading on register 30001 upward, and data for writing to at 40001 and upward.  I would have expected this to be a common situation, where the DTM Browser Generic ModbusTCP Device would be suitable, however on investigation, the ModbusTCP DTM Browser Generic Device is only able to access 40001 Holding Registers.

Has anyone come across the same issue?

Was there a workaround found (which didn't involve the use of DATA_EXCH / READ_VAR)?

Regards,

Bevan

[RoozeeR · Accepted solution]

As far as I know IO-scanning (DTM browser) only allows for reading/writing 4XXXX (%MWxxx) registers, meaning only the Modbus function codes 3, 16 and 23 are supported.

Other Modbus function codes, reading/writing 0xxxx, 1xxxx and 3xxxx are supported by function blocks only.

[Anonymous user]

https://www.se.com/ww/en/faqs/FA246092/

MBP_MSTR function code 15 allows to read 1x, 3x registers and can be used with M580 High End CPUs

[aamjad52114]

Could M340/M580 read input registers (3x) from third party modbus as well or is it just for schnedier products?

[Siddiqui]

Hi Amjad,

Yes M340 and M580 could read the input register (3x) from the third-party Modbus device as well.

In fact, any devices that support Modbus Serial or Modbus TCP protocol should be supported by the M340 as well as M580.

I hope it will provide help.

Best Regards,

Wasif

[aamjad52114]

Hi Wasif,

Thanks for the response. Is there documentation how to setup unity pro for reading 3x registers from 3rd party devices? 

[Siddiqui]

Hi Amjad,

There are many exchanges, it would be good if you mentioned using which CPU M340 or M580 or Quantum? You would like to read the 3x data from a third-party device? Easy for me to direct you in that way. 

Best Regards,

Wasif

[aamjad52114]

Hi Wasif,

 I am trying to read from input register 3x of skf analyst software using Quantum PLC ( 140 CPU 652 60 & 140 NOE 771 10). Please specify whether to use CPU or NOE ethernet

[AlastairF · Accepted solution]

M340 supports the READ_VAR and SEND_REQ commands that can be used to read 3X/ %IW values from remote ModBus devices.

M580 supports those commands and also MBP_MSTR command. To read 3X/ %IW you would need to use the Send ModBus Request

I'd suggest stay with READ_VAR as this can work with both with minor changes to the address field if required.

Look at the ADDM function to understand the addressing required.

The OBJ field defines the data type to be read.

Type of objects to read for Modicon M340 and M580 CPU:

• ’%M’: internal bits
• ’%MW’: internal words
• ’%I’: input bits
• ’%IW’: input words

[Siddiqui]

Hi Amjad,

You already had an answer for the M340 and M580. For the Modicon Quantum CPU you can MBP_MSTR.

Check the attached link for the FAQ from there you can get the sample program for reference purposes only.

https://www.se.com/ww/en/faqs/FA246092/

This is the same link as mentioned by Patrick Vaz.

I hope this will also provide help.

Best Regards,

Wasif

[FrancisBreysach]

Hello

I have made a developpement for Mars PetFood, in 2014 about this subject.

I join a little Guide, in French, but with a lot of screenshots who I explain how to generate several MBTCP Function code.

You have to use 140 NOE 77101 module with last version of FW. No Idea about 140NOE77111.

Using of MBP_MSTR() and Function code 15, implemented in NO77101 since FW V6.1.

Francis

[Leonardofb.Ferreira]

Hello everyone.

I recently made a Modbus communication using a PLC M340 with a third-party PLC using a read and write var block. With that, in the OBJ block I used %IW - Input Register. However, when converting integer to word and word to real, it didn't give me the right result. I'm trying to figure out what it could be. Does anyone know anything? Since I'm using %IW I don't know if I have to use another type of addressing.

[MatthewM]

Why are you converting INT to WORD to REAL?  You can just use INT_TO_REAL.

You may need a 1 word offset as some devices use IEC 0 based Modbus addressing, and others use Modicon 1 based addressing.  READ_VAR uses IEC 0 based so %IW0 is equivalent to 300001.

What data type is your source data?  If your source data is type REAL, then you will need to read two words and use WORD_AS_REAL to convert them into a REAL.  You may have to play with the high/low word order.

[ciupol]

Like MatthewM said do not convert INT to WORD to REAL. Conversion WORD to REAL messes things up. Here is an extract from Control Expert help for WORD_TO_*** function:

When converting the WORD data type to the DWORD, DINT, UDINT, REAL or TIME data type, the bit pattern of the input is transferred to the least significant bits of the output. The most significant bits of the output are set to zero.