SoMachine Basic Modbus Function Block Help

[JohnB315]

Hi all, I have a HACH sc200 controller with 2 sensors which I hope to connect an M221 plc to via Modbus RS485 in order to display the info on a HMI.
I am completely new to this and I am struggling to get my head around it.
I am struggling to understand how to set up the Read_Var function block to access the registers in the HACH.

For example, in the HACH manual some of the registers are:

Register# 40001, Data Type Integer, Length 1, Description Sensor meas.
Register# 40005, Data Type Float, Length 2, Description SensorTemp Meas.
Register# 40007, Data Type String, Length 6, Description Sensor Name.

How does this correspond to the options available in the Read_Var function block ?
The options are :
ObjType- 0 Read Multiple Words- Modbus 0x03
1 Read Multiple Bits - Modbus 0x02
2 Read Multiple Bits - Modbus 0x01
4 Read Multiple Words - Modbus 0x04
FirstObj -
Quantity -
IndexData-

I assume I need a Read_Var FB for each individual register ?

Any help to send me in the right direction would be greatly appreciated

John

 

[gclshortt]

http://www.plctalk.net/qanda/showthread.php?t=99112
The above thread may help you out.

For example, in the HACH manual some of the registers are:

Register# 40001, Data Type Integer, Length 1, Description Sensor meas.
Register# 40005, Data Type Float, Length 2, Description SensorTemp Meas.
Register# 40007, Data Type String, Length 6, Description Sensor Name.

The registers will show you the length and location. In order to read more than 1 word at a time use:
4 Read Multiple Words - Modbus 0x04

Here are a couple of good links on Modbus RTU:
https://www.rtaautomation.com/technologies/modbus-rtu/
http://www.simplymodbus.ca/FAQ.htm

I hope that this helps you out.
Regards,

 

[chud]

Not in english but you can see what they are doing

https://www.youtube.com/watch?v=ejsIh7hmbXo

 

[paraffin power]

http://www.plctalk.net/qanda/showthread.php?t=99112
The above thread may help you out.



The registers will show you the length and location. In order to read more than 1 word at a time use:
4 Read Multiple Words - Modbus 0x04

Here are a couple of good links on Modbus RTU:
https://www.rtaautomation.com/technologies/modbus-rtu/
http://www.simplymodbus.ca/FAQ.htm

I hope that this helps you out.
Regards,

Afraid this is wrong. Modbus Function code FC03 will read the 40000's, FC04 will read the 30000's

As an aside, from the SoMachine posts I've seen around here recently, I think we can agree it looks like it's garbage. How Schneider can ruin Codesys is beyond me, but they seem to have managed it.

 

[chud]

Afraid this is wrong. Modbus Function code FC03 will read the 40000's, FC04 will read the 30000's

As an aside, from the SoMachine posts I've seen around here recently, I think we can agree it looks like it's garbage. How Schneider can ruin Codesys is beyond me, but they seem to have managed it.

This post is regarding Somachine basic... Nothing to do with Codesys.
And the times I did use somachine it was basically codesys with a small amount of tweaks to it. 99% is codesys