User manual - COUNTER SLB-94
9.3.
EXAMPLES OF QUERY/ANSWER FRAMES
Examples apply for device with address 1. All values are represent hexadecimal.
Field description:
ADDR
Device address on Modbus network
FUNC
Function code
REG H,L
Starting address (address of first register to read/write, Hi and Lo byte)
COUNT H,L
No. of registers to read/write (Hi and Lo byte)
BYTE C
Data byte count in answer frame
DATA H,L
Data byte (Hi and Lo byte)
CRC L,H
CRC error check (Hi and Lo byte)
1. Read of device ID code
ADDR
FUNC
REG H,L
COUNT H,L
CRC L,H
01
03
00
21
00
01
D4
00
The answer:
ADDR
FUNC
BYTE C
DATA H,L
CRC L,H
01
03
02
20
C9
61
D2
DATA - identification code (20C9h)
2. Change of the device address from 1 to 2 (write to reg. 20h)
ADDR
FUNC
REG H,L
DATA H,L
CRC L,H
01
06
00
20
00
02
09
C1
DATA H - 0
DATA L - new device address (2)
The answer (the same as the message):
ADDR
FUNC
REG H,L
DATA H,L
CRC L,H
01
06
00
20
00
02
09
C1
42
Summary of Contents for SLB-94
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