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Device manual AS-i M4 Gateway Profibus DPV1 (AC1375, AC1376)
2012-02-23
Acyclic services for Profibus DPV1
Description
314
12
Acyclic services for Profibus DPV1
Description ................................................................................................................................ 314
Services for acyclic data transfer between DPM1 master and slave........................................ 315
Services for acyclic data transfer between DPM2 master and slave........................................ 315
DPV1 addresses in slot 0 for access via PLC........................................................................... 316
Examples................................................................................................................................... 318
DPV1 error messages............................................................................................................... 318
Syntax of the acyclic services in the DPV1 command channel ................................................ 321
Acyclic command in the DPV1 command channel ................................................................... 322
5808
12.1 Description
5810
A main focus of the Profibus power stage DPV1 is the additionally available acyclic data transfer. Field
devices can be assigned parameters and calibrated during operation, and acknowledged alarm
messages are made possible. The transfer of the acyclic data is carried out in parallel to the cyclic
data transfer, but with a low priority.
There is read or write access via virtual slots and indexes. Via slots and indexes, access to data
blocks of up to 244 bytes is possible. With Siemens Step7, slot 0 is always assigned to the device
itself and can always be addressed.
The device supports acyclic data transmission to DPM1 and DPM2 masters.
The access to parts of the data block in slot 0 is only possible by reducing the length. The offset of the
data is always 0 bytes for all data fields when access is made via slot 0 and index.
In case of a data length of 0, the entire length of the slot is returned. An error code is not returned in
case of length 0.
So, the M1 master flags can only be read in conjunction with the M1 digital inputs.
In case of access via slot 0, index 10, the projected parameters (PP) can only be written in conjunction
with the projected configuration data (PCD).
Given that the Profibus FDT scheme (FDT =
F
ield
D
evice
T
ool) only allows access without length
indication, the device shortens the data blocks always to the maximum data length intended for the
slot/index. If the requested data length exceeds 160 bytes (= max. intended length in the device), it is
also reduced to the length of the requested data block.
