I-7242D user manual
I-7242D DeviceNet/Modbus RTU Gateway User’s Manual, July 2006, Version 1.1 95/124
7.2.11 Fragmentation example
7.2.11.1 Unacknowledged Fragmentation example
Fragmentation of an I/O message is performed in an unacknowledged
fashion. Unacknowledged fragmentation consists of the back-back
transmission of the fragments from the transmitting module. The receiving
module(s) returns no acknowledgments (other than the CAN-provided Ack) on
a per-fragment basis. The Connection simply invokes the Link Producer’s
Send service as necessary to move the message without waiting for any
specific acknowledgment from the receiving module(s).
In this example, the polling consumed size is 10 bytes. Master must send
fragmented messages. Data=0102030405060708090A. Assume that the I/O
Connection has been established.
Unacknowledged:
Master
(MAC
ID
=0x0A)
Slave
(MAC
ID
=0x09)
_ Group 2 Message
| _ Destination MAC ID=0x09
| | _ Message ID =0
| | |
| | | _ Fragment Type= First Fragment, Fragment Count=0
| | | | ----------------------- 1
st
portion of the I/O data
ID=10 001001 101. Data= 00 01 02 03 04 05 06 07
_ Group 2 Message
| _ Destination MAC ID=0x09
| | _ Message ID =0
| | |
| | | _ Fragment Type= Final Fragment, Fragment Count=1
| | | | ----------------------- final portion of the I/O data
ID=10 001001 101. Data= 81 08 09 0A
