Data transfer
AS-i cycle
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Lenze · Decentralised frequency inverter 8400 motec (AS-Interface option) · EDS84DMOTASI EN 5.0 - 02/2019
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7.2
AS-i cycle
The complete AS-i cycle consists of:
• AS-i messages
Max. 31 messages (sum of the standard slaves connected to the network or the maximum of A
and B slaves)
• 1 management call
Consists of a parameter exchange or a command to a slave and an optional response.
• 1 call from the recording phase
Search for new slave addresses and optional response
• 1 reserve message (if required)
Cycle time
• The cycle time results from the following formula:
• When the maximum cycle time is determined, 33 messages are maximally estimated. Hence:
• Thus, approx. 200 cycles are passed per second.
• Thus, a standard slave can be provided 200 times per second with new output data and can
transmit its input data to the master.
Medium response time
• The medium response time results from the following formula:
• The
jitter
, which is the fluctuation around the medium response time, amounts to ...
• ± 2.5 ms for standard slaves;
• ± 5.0 ms for A/B slaves.
Cycle time = messages per cycle x max. message duration
Max. cycle time = 33 messages x 154
μ
s = 5.08 ms
Note!
Wherever A and B slaves are operated on one address, the cycle time is twice as long.
Medium response time = 0.5 x max. cycle time + max. message duration
Medium response time = 0.5 x 5.08 ms + 154
μ
s = 2.7 ms
Note!
Wherever A and B slaves are operated on one address, the medium response time is
twice as long (5.4 ms).
