Modbus and Scada

[vasovas]

Hi,

I want to read ML and MF from SM35 J R20 using Ignition SCADA. I get readings, but not the proper values. To make sure, 2 quick questions:

1. In PLC ladder, do I need HR reading FB, or Modbus SCAN EX is enough?

2. Start address for ML is 5100 and for MF is 7700?

[Joe Tauser]

1.  Yes, all you need in the SM35 are a Modbus config and SCAN_EX blocks for it to be a slave.  Is this serial or Ethernet?

 2.  Look in the Help for Slave Address Tables for the Enhanced Vision series.  The offsets are given in hex, and your SCADA probably is looking for decimal values.  If you can enter the addresses in hex it will be easier.

MLs - 7000h or 28672 = ML 0

MFs - 4000h or 16384 = MF 0

You may also have a problem with the byte order, as these are 32 bit values.  You may have to byte swap in Ignition to get the right value.  

Also, each register takes up two places in the SM35's memory.  Don't forget this when you determine addresses, i.e.  ML 2 = 28676.  

I'd start your testing by reading MIs, which are 16 bit and start at 0.  If Ignition follows standard Modbus addressing, this will be holding register 1.

Give us some examples of the exact addresses you're looking for and we can check the value you're reading.  Also post a screenshot of the Modbus config table from Ignition, as I am not experienced with this package.

Joe T.

 

[vasovas]

Hello, Mr. Tauser,

At first Happy and Prosperous New 2020!

Thank you for your advises, most of the issues solved now. Attached you can find ML tags that I can read now (L1...L6), plus Ignition Modbus Address Map, as requested by you. To get the right readings, I had to reverse the word byte order, as you supposed. Reading MI was piece of cake, so I did not attached anything, except Double-Single Tag, which is visible on the  Tag Browser (file Tags).

What still does not work, is MF tags reading - can you please double check the starting address, since I could not find the proper help file?

 

[vasovas]

OK, I found it.

The starting address for MFs is 8000h. 

Everything works normally now.

 

[Joe Tauser]

Thank you for getting back to us - there appears to be an error in the Help on the Enhanced Series Slave Address table.

@Cara Bereck Levy - can you verify this?

Joe T.

[Seb06]

100000 thanks mr Tauser about your suggestion to reverse byte order for 32 bytes value. I didn't understiood why had a problem of value from many hours... you saved my day   ! thansk a lot for your kind advices !