ifm
Supplementary device manual DeviceNet interface in the AS-i ControllerE (AC1318, AC1324), Target from 15
2012-02-29
Glossary of Terms
236
separation" between primary and secondary
side in the device (e.g. power supply to PELV
specification).
For this reason no separate PE conductor is
required in a PELV system. It is allowed to
ground circuits and / or bodies in a PELV
system.
Pictogram
Pictograms are figurative symbols which
convey information by a simplified graphic
representation.
Chapter
What do the symbols and formats
mean?
(
→
page
)
PLC configuration
Part of the CoDeSys user interface.
►
The programmer tells the programming
system which hardware is to be
programmed.
> CoDeSys loads the corresponding
libraries.
> Reading and writing the peripheral states
(inputs/outputs) is possible.
Polling
to poll = to count votes
The controller master fetches the data from
every participant in the system successively:
1. Master calls participant 1.
2. Participant 1 replies with its current data
(actual values).
3. Master transfers more data (target values)
to participant 1, if needed.
4. Participant 1 acknowledges reception of
the data.
etc. the same procedure for each further
participant.
Cyclical polling: AS-i master cyclically polls the
data of all
slaves in the bus (see above).
The data is updated in the
master after max.
5 ms. If A/B slaves are used, the
cycle time
can be extended to 10 ms.
Power-on delay time
The time required by the controller K6 from the
application of the voltage supply until all of the
following targets are reached:
both AS-i networks have reached normal
operation
the master has read the configuration data
of the CTTx slaves
the field buses can use the gateway
(optional)
the PLC program was started (optional).
Process image
Process image is the status of the inputs and
outputs the PLC operates with within one
cycle.
At the beginning of the cycle the PLC
reads the conditions of all inputs into the
process image.
During the cycle the PLC cannot detect
changes to the inputs.
During the cycle the outputs are only
changed virtually (in the process image).
At the end of the cycle the PLC writes the
virtual output states to the real outputs.
Profibus
PROFIBUS (
Pro
cess
Fi
eld
Bus
) is a standard
for fieldbus communication in automation
technology. There are three versions of
PROFIBUS, DP being the one most widely
used.
PROFIBUS-DP (decentralised periphery)
for the control of sensors and actuators by
a central controller in manufacturing
engineering and for networking of several
controllers among each other. Data rates
up to 12 Mbits/s on twisted two-wire cables
and/or fibre optics are possible.
PROFIBUS-PA (process automation) is
used for the control of measurement
devices by a process control system in
process technology and is suited for
hazardous areas (zones 0 and 1). Only a
limited current flows on the bus cables in
an intrinsically safe circuit so that even in
case of a problem no explosive sparks can
occur. A disadvantage of PROFIBUS-PA is
the relatively slow data transfer rate of
31.25 Kbits/s.
More information
