Read & write BOOL data via Modbus TCP between two Mico850 controllers

[ahaanwar2]

Dear all, glad to be here and I hope that we all can benefit from this great community.

I am trying to send and receive data between two Mico850 controllers, however my data types are different (Real, INT, and BOOL). Should I create more than Msg_modbus2, each for each type of data or one read and another write Msg_modbus2 are enough.

Moreover, the data carried in the msg_modbus2 are in WORD format, I can convert INT to WORD using the Convert function (any to word) and (any to int) directly, but how about converting the REAL and BOOL data types?

I can do without REAL as INT can be enough, but how to deal with BOOL data. Should I use some sort of arrays or what?

Please help me as I am frustrated.

Best,
Anwar

 

[Ken Roach]

Welcome to the PLCTalk forum community !

You are correct that you should use arrays by "packing" the BOOL tags into bits of a WORD type tag, and sending one or more 16-bit WORDs of data using Modbus/TCP.

Your logic on the receiving side should then "unpack" that data into the desired BOOL tags.

 

[ahaanwar2]

Thanks a lot for your response, could you please give me an example how to pack and unpack the booleans into word. What function to be used, and how to use it?

 

[drbitboy]

No function necessary: look up bit addressing modes in the help file.





Micro850 source: pack bits B3:0/0 and B3:1/0 into N7:0; send N7:0

   B3:0/0     N7:0/0
----] [---------( )-------


   B3:1/0     N7:0/1
----] [---------( )-------


(send word N7:0 data via Modbus)

Micro850 destination: receive N7:1; unpack bits into B3:2/0 and B3:2:1:

(receive data into word N7:1 via Modbus)



    N7:1/0     B3:2/0
-----] [---------( )-----

    N7:1/1     B3:2/1
-----] [---------( )-----

You may even be able to send words B3:0 and receive into B3:2.

 

[ahaanwar2]

Thanks for the help.


Do I need to use two MSG_Modbus2 functions for read and two for write?
Because I am reading and writing INT and BOOL variables. I mean, with the conversion using bit addressing do I need to still use a separate MSG_Modbus2 for Boolean variables?


Regards