Hi,

I have a system including the CM1241 (6ES7241-1CH32-0XB0) FW 2.2 which works with dataptr pointing to an array [0..1] of int.

But when increasing this buffer (example 0 ...11), Modbus works in background (send receive ok) with no error, but the buffer keeps filled with zeros.

However Modbusmaster_DB->ReceiveBuffer is filled with data, but somehow in case of bigger dataPtr buffer, the data doesn't move to dataPtr buffer.

I like to read-out multiple registers at time, how can I fix this?

I've searched the forum, but didn't get a solution for this...

Edit: when datalen equals bufferlen, then its filled so:

- Buffer 0...11 reading one register(len < 11) the buffer won't get filled

- Buffer 0...11 reading registers, len 12, the buffer will be filled...

So, should I use whole ram to make different buffers for different module reads?

Edit 2: this problem comes up with send as well. The code sends data, len in message is correct, but data send is 00, however dataPtr buffer [0] = 1... still Modbus block sends 0?

Thanks in advance,

John

Hi thanks!

I'm sending to my plc using Modbus Slave application.

PLC has 3 buffers: dataPtr [0...11], Send (same data type) and Receive.

When data is received, it will be moved to the receive buffer.

I there can readout like this (from application, so RX = send by plc):

Thank you,

But how can I use this kind of addressing in SCL?

I've read this: https://support.industry.siemens.com/tf/WW/en/posts/any-pointer-in-scl/50677?page=0&pageSize=10 

but there they use any, not variant which the default function block of Siemens is.

Edit: Also the problem is: receiving 24bytes isn't the problem, but receiving less than 24 bytes is a problem, then the db_keller is filled with zeros.

Let me explain: DB_Keller.dataPtr (struct of 2 ints) and asking 2 registers, results in for example [0] 12345 and [1] 54321.

Exact same routine, but bigger struct (12 ints) , the exact same code I would expect [0] and [1] gets the same value, 2-11 filled with zeros. But in this particular case, also 0 and 1 are filled with zeros.

Best regards,

John