0X03) Read The Holding Registers (Read Ao Readback Values ) - ICP DAS USA iNS-308 User Manual

iNS-308 User Manual
7.2.3 03(0x03) Read the Holding Registers
(Read AO Readback values )
This function code is used to readback either the current values in the holding registers or the Analog
Output value from the iNS-308. These registers are also used to store the preset valuesfor the Digital
Counter, the host watchdog timer, the module name and the TCP timeout, etc.
[Request]
Byte Description
00 Net ID (Station Number)
01 Function Code
02-03 Starting AO Address
Number of Registers
04-05
(Channels)
[Response]
Byte Description
00 Net ID (Station Number)
01 Function Code
02 Byte Count
03 Register Values
[Error Response]
Byte Description
00 Net ID (Station Number)
01 Function Code
02 Exception Code
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Size
1 Byte 1 to 247
1 Byte 0x03
Byte 02 = high byte
2 Byte
Byte 03 = Low byte
Word Count
2 Byte Byte 04 = high byte
Byte 05 = Low byte
Size
1 Byte 1 to 247
1 Byte 0x03
Byte Count of the Response
1 Byte
( n = Points x 2 Byte )
n= 1; Byte 03 = high byte
n= 2; Byte 04 = Low byte
n Byte .......
n= m; Byte m+1 = high byte
Byte m+2 = Low byte
Size
1 Byte 1 to 247
1 Byte 0x83
Refer to the Modbus Standard
1 Byte
Specifications for more details
Value
Value
Value
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