Siemens BW500 to Compactlogix over Ethernet/IP

[Echo_Bay1]

I have a Siemens BW500 Weightometer talking to a AB Compactlogix over ethernet/ip, the comm link works fine but when the data is brought into the controller the data does not make any sense, I have read that Siemens treats there bits and words backwards to Allen Bradley, and if so, do I need to invert the single word first then use a bit field Distribute instruction to invert the 2 integers into a single Uint32.

 

[drbitboy]

can you say what you expect to see? and then what you are actually seeing? It would be easiest if you showed the values in hexadecimal, but it is not necessary.

 

[AlfredoQuintero]

I have a Siemens BW500 Weightometer talking to a AB Compactlogix over ethernet/ip, the comm link works fine but when the data is brought into the controller the data does not make any sense, I have read that Siemens treats there bits and words backwards to Allen Bradley, and if so, do I need to invert the single word first then use a bit field Distribute instruction to invert the 2 integers into a single Uint32.

Siemens PLC use processors with "Big-endian" or "Motorola" style MSB:LSB data representation, whereas CompactLogix processors use "Little-endian" or "Intel" style LSB:MSB representation. That means at either side you need to do swapping to make sense of the data being received, or swap the data before sending it to the other side, so the other side can make sens of it. If you need more details on how to do the swapping please let me know.

 

[Echo_Bay1]

I will have to do the swapping at the AB processor end, if you have a example or a better way please let me know

 

[Ken Moore]

You have to swap the bytes from Siemens. Use the SWPB instruction in the CompactLogix.