ISON IS-DS5150, User Manual, Page: 54 / 66

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01(0x01) Read the Status of the Coils (Readback DOs)
This function code is used to read either the current status of the coils or the current digital output
readback value.
[Request]
Byte Description Size Value
00 Net ID (Station Number) 1 Byte 1 to 247
01 Function Code 1 Byte 0x01
02-03 Starting DO Address 2 Bytes
Refer to the Modbus address depends on your
slave device for more details.
Byte 02 = high byte
Byte 03 = low byte
04-05 Number of Points (Channels) 2 Bytes
Byte 04 = high byte
Byte 05 = low byte
[Response]
Byte Description Size Value
00 Net ID (Station Number) 1 Byte 1 to 247
01 Function Code 1 Byte 0x01
02 Byte Count 1 Byte
Byte Count of the Response
( n = (7)/8 )
03 Data n Bytes
n= 1; Byte 03 = data bit 7 to 0
n= 2; Byte 04 = data bit 15 to 8
.......
n= m; Byte m+2 = data bit (8m-1) to 8(m-1)
[Error Response]
Byte Description Size Value
00 Net ID (Station Number) 1 Byte 1 to 247
01 Function Code 1 Byte 0x81
02 Exception Code 1 Byte
Refer to the Modbus Standard Specifications for
more details