ICP DAS, ZT-257x DIO Data Concentrator Quick Start Guide, v1.0
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Copyright © 2016, by ICP DAS Co., LTD. All Rights Reserved
5.3
Modbus Register
5.3.1.
01 (0x01) Read Coils
This function code is used to read the temporary Digital Output values from a range of
virtual/logical channels on the ZT-257x module.
Request
Byte Description
Length Value
00
Address
1
0x01 to 0xF7 (1 to 247)
01
Function Code
1
0x01
02-03
Starting Channel
Number or
Address Mapping
2
DO (Temporary Output)
0x0000 to 0x0117
DI (Temporary Input)
0x0200 to 0x0317
Safe Value
0x0400 to 0x0517
Check Router Alive
Channel
<See Note 1>
0x0601 to 0x061F
04-05
Output Channel
Number or Bit Count
2
0x0001 to 0x0118
(
Bit Count)
Response
Byte Description
Length Value
00
Address
1
0x01 to 0xF7 (1 to 247)
01
Function Code
1
0x01
02
Byte Count
1
The Byte Count of the Response
[B = (Bit Count + 7)/8]
03
Bit Values
B
(Bit Values)
Error Response
Byte Description
Length Value
00
Address
1
0x01 to 0xF7 (1 to 247)
01
Function Code
1
0x81
02
Exception Code
1
Refer to the Modbus standard for more details