CAS CI-600D Series - MODBUS-RTU Protocol; MODBUS-RTU Data Format; MODBUS Supported Functions

The Delay parameter present in the paragraph SERIAL COMMUNICATION
SETTING allows for a further delay in the instrument response, and this directly influences
the number of possible queries in the unit of time.
For additional inf
ormation on this protocol, refer to the general technical specification
PI_MBUS_300.
In
general, the query and response to and from a slave instrument are organised as follows:
FUNCTION 3: Read holding registers
(PROGRAMMABLE REGISTER READING)
QUERY
Address Funcion Add. Register1 No. register 2 bytes
A 0x03 0x0000 0x0002 CRC
Tot. bytes = 8
RESPONSE
Address Funcion No.bytes Register1 Register2 2 bytes
A 0x03 0x04 0x0064 0x00C8 CRC
Tot. bytes = 3 + 2*No. register+2
where: No. registers= number of Modbus register to be read, starting from the Address
1° register;
No. bytes = number of data bytes to follow;
FUNCTION 16: Preset multiple registers (MULTIPLE REGISTER WRITING)
QUERY
Addr Func
Add.
Reg.1
No.reg.
No.
bytes
Val.
Reg. 1
Val.
Reg. 2
2 bytes
A 0x10 0x0000 0x0002 0x4 0x0000 0x0000 CRC
Tot. bytes = 7 + 2*No. register+2
RESPONSE
Address Funcion Add.Reg.1 No.reg. 2 bytes
A 0x10 0x0000 0x0002 CRC
Tot. bytes = 8
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