Hitachi WJ200-001S Instruction Manual page 544

Please use "Signed" format when range of internal register data include minus value, as seen Example 3. If
you use "Unsigned" erroneously, you will get exceptional response in some cases.
When value of P057 = -10
Reading holding register [03h], Target Register ： E xternal Register
Query:
No
1 Slave address
2 Function code
3 Register start address (high order)
4 Register start address (low order)
5 Number of holding registers (high order)
6 Number of holding registers (low order)
7 CRC-16 (high order)
8 CRC-16 (low order)
Response:
No Field Name
1 Slave address
2 Function code
3 Data size (in bytes)
4 Register data 1 (high order)
5 Register data 1 (low order)
6 CRC-16 (high order)
7 CRC-16 (low order)
*No exception occurs when reading out data. The data read correctly.
Field Name
Example
(Hex)
01
03
02
FF
F6
79
F2
Example
(Hex)
01
03
40 Register address value = Register
Number - 1
02
00
One register
01
30
0A
FFF6h represents -10 in two's
compliment
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