[foxboro] Modbus Communications

When using a IOUT block can you disable/ignore the readback from the external 
device?

We are trying to communicate via ModBus to a Atlas Copco Compressor using an 
FBM224. The compressor came with its own controller called a Elektronicon, but 
it is proprietary so a device called a Combox-S sets between the I/A system and 
the compressor. Everything works well with the exception of registers 
42001,42002 and 42004, which use a function code 06. Problem is that no matter 
which one of these registers send a request(in which the compressor does 
respond to correctly), only 42001 gets a readback, and it is the value that was 
sent by the other register. Atlas Copco is telling us that these registers in 
the Combox-S use a shared register and the Foxboro System needs to ignore the 
readback. If this is true is this normal?  There are other registers 
41062,41062,41064,41065 that also use the function code 06 that work as what I 
call normal, only the register that sends the request gets the readback. When 
setting up the transaction table there is a selection for WRITE ONLY and one 
for READ/WRITE.  When selecting WRITE ONLY it does not establish communications 
with the Combox-S.



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