Comtrol IO-Link Master EIP-4 - Manual (Page 21)

IO-Link Master EtherNet/IP Reference Manual: 2000589 Rev. A Chapter 2. Functionality Descriptions - 21
Clear Event Code in PDO Block and Clear Event After Hold Time Process-Hold Time Expires
2.1.4. Clear Event Code in PDO Block and Clear Event After Hold Time Process-
Hold Time Expires
This illustrates clearing the event code in the PDO block and clearing the event after the hold time process
with the hold time expired.
2.2. ISDU Handling
The IO-Link Master provides a very flexible ISDU interface that is used by all supported industrial protocols.
The ISDU interface contains the following:
• An ISDU request may contain one or multiple individual ISDU read and/or write commands.
• Individual ISDU command based byte swapping capabilities.
• Variable sized command structures to allow access to wide range of ISDU block sizes.
• A single ISDU request may contain as many ISDU read and/or write commands as allowed by the
industrial protocol payload. For example, if an industrial protocol provides up to 500 byte read/write
payloads, then an ISDU request may contain multiple commands of various lengths that can total up to
500 bytes in length.
• For the ControlLogix family of EtherNet/IP PLCs, both blocking and non-blocking ISDU request methods
are provided.
- The IO-Link Master implements blocking ISDU requests by not responding to an ISDU request
message until all commands have been processed.
- The IO-Link Master implements non-blocking ISDU requests by:
• Responding to an ISDU request message immediately after receiving and verifying the ISDU
request.
• Requiring the PLC to monitor the ISDU request status with read messages. The IO-Link Master
will not return a completed status until all of the ISDU commands have been processed.