I-7242D user manual
I-7242D DeviceNet/Modbus RTU Gateway User’s Manual, July 2006, Version 1.1 109/124
8.3
“Read Holding Registers” Command (0x03)
Read the binary content of holding registers in the slave. The query
message specifies the starting register and quantity of registers to be read.
And the register data in the response message are packed as two bytes per
register, with the binary contents right justified within each byte.
Frame Field
Description
Starting Address (Hi)
Starting Address (Lo)
Address of 1
st
output register
No. of Points (Hi)
Query
No. of Points (Lo)
Number of output registers
Byte Count
Number of data bytes=number of output registers x 2
Data (first register/MSB)
Data (first register/LSB)
…..
Data (last register/MSB)
Response
Data (last register/LSB)
Byte swap=”Swap 2 bytes” (or “No swapping”)
Data length=Value of the “Byte Count” field
Data location=Address in the gateway’s “AO” memory
8.4
“Read Input Registers” Command (0x04)
Read the binary content of input registers in the slave. The query
message specifies the starting register and quantity of registers to be read.
And the register data in the response message are packed as two bytes per
register, with the binary contents right justified within each byte.
Frame Field
Description
Starting Address (Hi)
Starting Address (Lo)
Address of 1
st
input register
No. of Points (Hi)
Query
No. of Points (Lo)
Number of input registers
Byte Count
Number of data bytes=number of input registers x 2
Data (first register/MSB)
Data (first register/LSB)
…..
Data (last register/MSB)
Response
Data (last register/LSB)
Byte swap=”Swap 2 bytes” (or “No swapping”)
Data length=Value of the “Byte Count” field
Data location=Address in the gateway’s “AI” memory
