AH500 Programming Manual
6-416
API
Instruction code
Operand Function
1808 MODRW
S
1
, S
2
, S
3
, S, n
Reading/Writing the MODBUS data
Device
X Y M S T C HC D L SM SR E PR K 16# “$”
DF
Pulse instruction
16-bit instruction (11 steps) 32-bit instruction
- AH500 -
Symbol:
S
1
：
Unit address Word
S
2
：
Function code Word
S
3
：
Device address Word
S
：
Register involved in the reading/writing of the data Bit/Word
n
：
Data length Word
Explanation:
1. The operand S
1
should be within the range between 0 and 255.
2. S
2
: The function code
For example:
1 (16#01): The AH500 series PLC reads the data from several bit devices which are not
discrete input devices.
2 (16#02): The AH500 series PLC reads the data from several bit devices which are discrete
input devices.
3 (16#03): The AH500 series PLC reads the data from several word devices which are not
input registers.
4 (16#04): The AH500 series PLC reads the data from several word devices which are input
registers.
5 (16#05): The AH500 series PLC writes the state into a bit device.
6 (16#06): The AH500 series PLC writes the data into a word device.
15 (16#0F): The AH500 series PLC writes the states into several bit devices.
16 (16#10): The AH500 series PLC writes the data into several word devices.
Only the function codes mentioned above are supported, and other function codes can not be
executed. Please refer to the examples below.
3. S
3
: The device address
If the device address is illegal, the error occurs. The error code is stored in the error log.
4. S: The register involved in the reading/writing of the data
The data which will be written into the external equipment is stored in the register in advance.
The data which is read from the external equipment is stored in the register.
5. n: The length of the data
The size of the data can not be larger than 240 bytes. For the communication commands
related to the coils, the unit of the data is the bit, and n should be within the range between 1
and 1920. For the communication commands related to the registers, the unit of the data is the
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