Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 171)

Publication 1753-UM001C-EN-P - March 2010 171
Peer-to-peer Communication Overview Chapter 16
Peer-to-Peer Profile III: Medium & Cleanroom
This profile provides medium data throughput for applications where
only a moderate data update rate is required and where the Worst
Case Reaction Time is not a critical factor. It is well-suited for virtual
private networks (VPN), where data exchange is slow due to safety
devices (firewalls, encoding/decoding), but error-free.
Medium & Cleanroom Characteristics
TIP
Normally use the profile Medium & Noisy
(see page
172 ).
Minimum Ethernet
network requirements
Medium or Fast
10 MBit (10 Base T) or 100 Mbit technology
(100 Base TX) or network with both 10 MBit
and 100 MBit components.
LAN switches required.
Clean
No loss of data due to traffic overload, harsh
environmental conditions or network defects.
Time for
≥
0 repetitions.
Characteristics of the
communication path Moderate delays
ResponseTime
≤
ReceiveTMO (otherwise ERROR)
Variables
ResponseTime manually set in the Peer-to-Peer Editor
ReceiveTMO manually set in the Peer-to-Peer Editor
WDZ manually set in the controller properties
Suitable HH network
profile Fast
Medium (
≤
10 controllers in a Token Group)
Peer-to-Peer
parameter presets
•
QueueLen = 3
•
Communication Time Slice large enough to process and send
all data defined for transmission in one CPU cycle.
•
ResentTMO
– if ReceiveTMO
≥
2 x WDZ, then
ResendTMO = ResponseTime (
≥
0 Resends possible)
– if ReceiveTMO < 2 x WDZ, then
ResendTMO = ReceiveTMO
•
AckTMO = ReceiveTMO or AckTMO = AckTMOMax,
whichever is smaller
•
ProdRate = ResponseTime
ч
4