Modbus/Rtu Protocol - Circutor CVM k2 User Manual

CVM k 2 CVM k 2
8. COMMUNICATIONS
8.1. MODBUS/RTU PROTOCOL ©
CVMk2 uses the modbus/RTU © as the communications protocol on the COm2 port. This is a
question-response based protocol. The question frame format is:
NPAAxxxxyyyy CRC.
PN: The number of the peripheral configured for the system.
AA: modbus function to be executed.
xxxx: System's memory position where the function should be begin. (Example: If AA=04 the
function is read only).
yyyy: Read positions, from the xxxx position, to be read or written. (This depends on the AA
function).
CRC: Code for detecting 16 bit errors. (automatically generated).
The response format is
NPAABBCCCC..CRC
PN: Number of the peripheral that responds
AA: function that responds.
BB: Number of bytes in the response.
CCCC: Registry value.
...
CRC: Error detection registry.
for more information, see the standard modbus© protocol.
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