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CP 541 with S5-95F/S5-1 15F
5.3.1
Local Cycle Time for CP 541
Introduction
Definition
Variables Affecting
the LCT
5-10
Based on the cycle time in SINEC L1, we use the local cycle time for opera-
tion of the CP 541.
You need the local cycle time to verify the receive safety time.
The local cycle time is the time elapsing until all the maximum possible mes-
sages between the CP 541 and the connected programmable controller have
been exchanged once. We distinguish between the local cycle times for send-
ing and receiving.
In the worst case, a message received by the CP 541 from SINEC L2 must
wait until it is received by the connected programmable controller. This also
applies to the opposite direction.
The local cycle time (LCT) is affected by the following variables:
Number of messages
For the number of messages, you must list all the messages sent and re-
ceived from the viewpoint of the connected programmable controller.
Length of individual messages
The length of individual messages directly contributes to the transit time
of the individual message.
Receive delay time (UPDL, see Appendix C.4)
You use parameter UPDL to set the receive delay time for the connected
programmable controller; with failsafe programmable controllers S5-95F
and S5-115F, the time must not drop below this value for safety-related
communication.
Send delay time (POL, see Appendix C.4)
When this time has elapsed, the connected programmable controller will
be interrogated for a new send message.
Priority list (PRI, see Appendix C.4)
The CP 541 passes on the received messages from all stations specified in
the priority list to the connected programmable controller.
If no particular priority list is defined, all possible stations are entered as
standard.
Communications Processor CP 541
EWA 4NEB 812 6188-02
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