100 Appendix
WAGO-I/O-SYSTEM
750
750-657 IO-Link Master
Manual
Version 1.0.2, valid from FW/HW-Version 02/01
11.1.3.1 Fragmentation service "IOL_PD"
The "IOL_PD" service is identified by Protocol ID 0 and can be used within a
segment of the cyclic process image if the segment of a port is smaller than the
process image of an IO-Link device (e.g. segment width 4 bytes and process
image of the device 16 bytes).
It is used to transfer the process data of the IO-Link devices in a fragmented
manner.
The simple message header is used because the user data of an IO-Link device is
max. 32 bytes.
Telegram structure for fragmented process data:
Figure 40: Telegram structure for fragmented process data
Example:
An IO-Link device has a process data length of
8 bytes
, which should be
transferred in a 4-byte port segment.
•
Port segment length
= 4 Byte
•
Byte 0
= MBX_C/S (1 Byte)
•
Byte1 bis 3
= MBX_DATA (3 Byte)
The following data is transferred sequentially:
•
1st cycle: MBX_Header (simple header from Protocol ID 0 and length)
+ process data fragment 1 (
2 bytes
)
•
2nd cycle: Process data fragment 2 (
3 bytes
)
•
2nd cycle: Process data fragment 3 (
3 bytes
)
More information about fragmenting is available in sections "Fragmented Process
Data" and "Data Exchange".
Port segment n-1
Port segment n
Port segment n+1
0 LEN*
Process data fragment
MBX_C/S
MBX_DATA
* Mailbox 2.0 header for Protocol ID 0,
max. data 128 bytes
