ELAU PacDrive M, Operating Manual

Page: 55 / 88

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PacDrive™ M field bus PROFIBUS-DP page 55
6.4 PROFIBUS-DP Slave
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Table 6-15: PROFIBUS-DP slave / Parameter IOTrigger
NOTE
Not all combinations of DataExMode and IOTrigger are sensible.
IO matching by
field bus card IRQ
/ 1 Matching is done by the interrupt of the field bus card. The
interrupt takes place as soon as the DPM of the card is no
longer used by the Profibus card software and access by
MAx4 firmware is admissible. At the end of the copying
process, a receipt for MAx4 firmware enabling of the DPM
range is sent at the end of the task started by the trigger. It
reads the DPM and sends the data to the bus or writes the
data received into the Dpm. The card enables the DPM
and triggers an interrupt. This procedure repeats cyclically.
The frequency depends on the data volume to be
transmitted, the baud rate and the DataExMod set.
IO matching by
IEC program / 2 Matching is done by the IEC program. The copying task is
started by calling the system component PrSlTrigger().
The copying task carries out a copying procedure and
waits for the next PrSlTrigger() call.
IO matching by
real-time bus / 3 Matching is done by the real-time bus tact. The trigger
signals are sent with the intervals laid down in the
CycleTime parameter of the real-time bus.
DataExMode IOTrigger Explanations
sync. buffered
firmware
access / 0 IO matching by
IEC program /
2 IEC control active; i.e. the IEC function
PrMaTrigger is used-> IEC program triggers
IO match. After the IO match the Profibus is
triggered, i.e. a Profibus cycle is started.
+ minimal average jitter; data consistency
- complex
See also PROFIBUS-DP libraries / IEC
examples in the EPAS-4 online help.
IEC control active / asynchronous; as
above. In addition, the IEC function
PrMaGetServerState() is used.
+ consistent data can be reached even in
case of an IEC task priority greater than the
priority of the IO server.
See also PROFIBUS-DP libraries / IEC
examples in the EPAS-4 online help.
sync. buffered
firmware
access / 0 IO matching by
field bus card
IRQ / 1 no IEC control; i.e. no IEC function is used
+ very easy handling
- relatively large jitter
Trigger source Meaning