RSTi-OM User Manual
Section 13
GFK-3212A
Jun 2021
Functionality Descriptions
140
Integer (16-Bit Word) ISDU Request Command Format
This table shows an integer (16-bit word) ISDU request command format with an SLC, MicroLogix,
PLC-5, or Modbus/TCP.
Name
Data Type
Parameter Description
Byte Swapping /
RdWrControlType
UINT
Provides the control, type, and byte swapping of the
ISDU command
Bits 0-3, Type Field:
0 = NOP (No operation) 1 = Read operation
2 = Write operation 3 =
Read/Write “OR”
4 = Read/Write “AND”
Bits 4-7, Control Field:
0 = Single/Last Operation (length can vary from to 1 to
232) 1 = Nested batch command
–
fixed 4 byte data area
2 = Nested batch command
–
fixed 8-byte data area 3 =
Nested batch command
–
fixed 16-byte data area 4 =
Nested batch command
–
fixed 32-byte data area 5 =
Nested batch command
–
fixed 64-byte data area
6 = Nested batch command
–
fixed 128-byte data area 7
= Nested batch command
–
fixed 232-byte data area
Bits 8-11:
0= No byte swapping.
1= 16-bit (INT) byte swapping of ISDU data. 2= 32-bit
(DINT) byte swapping of ISDU data.
Bits 12-15:
Set to zero. Unused.
Index
UINT
The parameter address of the data objects in the IO-Link
device.
Subindex
UINT
The data element address of a structured parameter of
the data objects in the IO-Link device.
Datalength
UINT
Length of data to read or write.
For nested batch commands, the data length can vary
from 1 to the fixed data area size.
Data
An array of
USINTs,
UINTs, or
UDINTs.
The size of an array is determined by the Control field in
RdWrControlType.
Note: Data is valid only for write commands.
ISDU Response Message Format
Standard ISDU Response Command Format
The following table shows the standard ISDU response command format with ControlLogix PLCs.
Name
Data Type
Parameter Description
Status
USINT
Indicates the byte alignment and status of the command
response.
Byte swapping, bits 0-3:
0= No byte swapping.
1= 16-bit (INT) byte swapping of TX/RX ISDU data. 2= 32-bit
(DINT) byte swapping of TX/RX ISDU data.
Status, bits 4-7:
0 = NOP (No operation)
1 = In process (Only valid for non-blocking requests) 2 =
Success
3 = Failure: IO-Link device rejected the request. 4 = Timed out:
IO-Link device did not respond