ABB TMD-T4 Instruction Manual - page 5
TMD-T4
protocol communication - instruction manual IM148-U-AB v0.92 pag. 5 / 12
READING OF THE REGISTERS (Function Code $ 03)
Reads the binary contents of holding registers ( 2X references) in the slave.
Broadcast is not supported.
The Query message specified the starting register and quantity of register to be read.
QUERY:
START OF
FRAME
ADDRESS
FIELD
FUNCTION
CODE
START
ADDRESS
No. OF
REGISTERS
ERROR
CHECK
END OF
FRAME
START OF FRAME
= Starting message marker.
ADDRESS FIELD
= TMD device address (01...F7 HEX)
(1 byte).
FUNCTION CODE
= Operation code ( 03 HEX)
(1 byte).
START ADDRESS
= First register address to be read
(2 byte).
No. OF REGISTERS = Number of registers ( max 32) to be read
(4 byte for 1 measure value).
ERROR CHECK
= Check sum.
END OF FRAME
= End message marker.
WARNING:
It is possible to read more than one variable at the same time (max 16) only if their addresses are consecutive and
the variables on the same line cannot be divided.
The register data in the response message are packet as two bytes per register, with the binary contents right
justified within each byte.
For each register, the first byte contains the high order bits and the second contains the low order bits.
RESPONSE:
START OF
FRAME
ADDRESS
FIELD
FUNCTION
CODE
No. OF
BYTES
D0, D1, …, Dn
ERROR
CHECK
END OF
FRAME
START OF FRAME
= Starting message marker.
ADDRESS FIELD
= TMD device address (01...F7 HEX)
(1byte).
FUNCTION CODE
= Operation code ( 03 HEX)
(1 Byte).
No. OF SEND BYTES = Number of data bytes ( 00...?? HEX)
(1 byte). 1 register requires 2 data bytes.
D0, D1, .., Dn
= data bytes ( 00...?? HEX)
(Nr. of register x 2 = n. byte).
ERROR CHECK
= Check sum.
END OF FRAME
= End message marker.
See the TABLE OF TMD REGISTERS.