Modbus read one register address is store 2 byte data

Hello,

I have a device that connects via modbus and I need to read data from a register address that is stored in 2 bytes.

The addres are 0008h-0009h

Can help me with this question?

Best Regards

Marco Wilson

 Hello,

MWilson_PT

Hello,

I have a device that connects via modbus and I need to read data from a register address that is stored in 2 bytes.

The addres are 0008h-0009h

Can help me with this question?

Best Regards

Marco Wilson

very sry,  really it's not clear to me all about register address description. 2 bytes, you mean 2 registers or one register where address is 16#89 or 16#98 or you need read from 2 registers - first is 16#08 and second is 16#09? Really if you want some good answer you need ask with clear question and description of problem. What type of register? maybe3 snippet from documentation where this info is can be good to see here, attach it as jpg inside ZIP.

Hello,

I try clarify my question. I have one energy meter thats comunicate by modbus. 

I have one array to store the values that i receive by modbus. In the next image i send one table with the register address.

My question is in the first 6 lines of the table. 

Best regards

Marco Wilson

Hello,

so in case you have data as Holding register, you need simply use my mentioned math. Look at screenshot from docs, you have there also message that data are stored in 2 bytes format (standard) so in this case your LEN parametr can be set to 1 (one register read), in case you have buffer set as WORD structure f.ex. There is also clear in Note 1 that in case DATA are 4 bytes long, you need read 2 registers at one time, in this case I expect LEN set to 2, with buffer WORD structure. Lets example for first register 16#0000 and 16#0001, here you need do that math like 40001 (is holding register)+0 (your first address 16#0000 in dec format)->40001, LEN set to 2 (you need read 2 registers to have REAL number inside buffer). Address 16#0001 is simply added to driver with LEN=2 so its enough set destination address in CLIENT block to 40001 (formal first register 16#0000). After send request you can have answer in your buffer data from first register with REAL number. Here pay attention, it can be possible that you'll need swap words to have correct expected value so check this for sure.

Hello,

Thanks for reply,

I have 1 struct with 20 positions to store the values. So in my data_len I put the number 2 and i will receive the data from the data_ptr. Thats correct?

Sorry my questions but this theme is new for me.

Best Regards

MArco Wilson

Hello,

I try the soluction of the Duris_I but if I modify the value but is not work.

With my actual configuration I have access to all parameters except the first 3 of the table.

I need oly read the values.

best Regard

Marco Wilson

​ I0.0​ is insular.I0.1As a stop, use 24V input. DC input is 24VDC equal to relay Q0.0 to Q0.5 Integrated functions with mobile axelsThen share it with my computer to understand.

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​ I0.0​ is insular.I0.1As a stop, use 24V input. DC input is 24VDC equal to relay Q0.0 to Q0.5 Integrated functions with mobile axelsThen share it with my computer to understand.

 What do you mean?