ICP DAS USA ET-2217CI, Руководство пользователя

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ET-2200 Series Ethernet I/O Modules
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6.2.2 02(0x02) Read the Status of the Input (Read DI values)
This function code is used to read the current Digital Input value from the ET-2200 series module.
[Request]
Byte Description Size Value
00 Net ID (Station Number) 1 Byte 1 to 247
01 Function Code 1 Byte 0x02
02-03 Starting DI Address 2 Bytes
Refer to Section 6.3 or 6.4 “Modbus Register
Table” to find the address.
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 0x02
02 Byte Count 1 Byte
Byte Count of 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 0x82
02 Exception Code 1 Byte
Refer to the Modbus Standard Specifications
for more details