Simex SRP-457, User Manual

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User manual - METER SRP-457
10.3. 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 the displayed value (measurement), SRP-457 device address = 01h:
ADDR FUNC REG H,L COUNT H,L CRC L,H
01 03 00 01 00 01 D5 CA
a) The answer (we assume that the measure result is not out of range):
ADDR FUNC BYTE C DATA H,L CRC L,H
01 03 02 00 FF F8 04
DATA H, L - displayed value = 255, no decimal point.
Decimal point position can be read from reg. 03h.
b) The answer (if an error occur):
ADDR FUNC ERROR CRC L,H
01 83 60 41 18
ERROR - error code = 60h, bottom border of the measurement range is exceeded
2. 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 21 F2 21 91
DATA - identification code (21F2h)
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