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iNS-316 User Manual
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2022 ICP DAS CO., Ltd. All Rights Reserved.
- 48 -
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-316. 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
Size
Value
00
Net ID (Station Number)
1 Byte
1 to 247
01
Function Code
1 Byte
0x03
02-03
Starting AO Address
2 Byte
Byte 02 = high byte
Byte 03 = Low byte
04-05
Number of Registers
(Channels)
2 Byte
Word Count
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
0x03
02
Byte Count
1 Byte
Byte Count of the Response
( n = Points x 2 Byte )
03
Register Values
n Byte
n= 1; Byte 03 = high byte
n= 2; Byte 04 = Low byte
.......
n= m; Byte m+1 = high byte
Byte m+2 = Low byte
[Error Response]
Byte
Description
Size
Value
00
Net ID (Station Number)
1 Byte
1 to 247
01
Function Code
1 Byte
0x83
02
Exception Code
1 Byte
Refer to the Modbus Standard
Specifications for more details