IFM Ecomat 300 AC1355, Supplementary Device Manual

Page: 244 / 248

Terms, abbreviations
15-4
PELV PELV =
P
rotective
E
xtra
L
ow
V
oltage
Functional extra low voltage with safe separation, grounded variant of SELV.
Extra low voltage with safe separation (grounded variant of SELV). The
specification as PELV system to IEC364-4-41 (initially DIN VDE 0100-
410:1997-01) covers a measure to protect against direct and indirect contact
with dangerous voltages by a "safe 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.
Pictograms Image symbols which convey information by a simplified graphic
representation.
→ page 1-1 , chapter What do the symbols and formats stand for?
Polling to poll = to count votes
The controller master fetches the data from every participant in the system
successively:
master calls participant 1
participant 1 replies with its current data (actual values)
master transmits more data (preset values) to participant 1 if needed
participant 1 acknowledges receipt of the data
etc., the same procedure for all other participants.
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.
Profibus Fieldbus system for larger data volumes, it requires special cables, complex
connection technology. It is available in different variants as Profibus FMS, DP
or PA. The Profibus DP can be used as a supplier for AS-i over greater
distances. Corresponding
→
gateways are available.
Profibus FMS Profibus FMS (
F
ieldbus
M
essage
S
pecification) for networking of controllers.
Was replaced by Profibus DP.
Profibus DP Profibus DP (
D
ecentralised
P
eriphery) to trigger sensors and actuators by a
central controller in production technology. In particular the numerous standard
diagnostic options are important. More applications are the connection of
"distributed intelligence", i.e. networking of several controllers among each
other (similar to
→ Profibus FMS). Data rates up to 12 Mbits/s on twisted two-
wire cables and/or fibre optics are possible.
Profibus DPV1 The functional extensions to Profibus DP (in short: DP) provided for in the
Profibus standard IEC 61158 complement the cyclic communication functions
of Profibus DP by the possibility of acyclic required data transfer.
Profibus PA Profibus PA (
P
rocess
A
utomation) is used to control field devices by means of
a process control system in process technology. This version of PROFIBUS is
suited for hazardous areas (Ex zones 0 and 1). Only a small current flows on
the bus cables in an intrinsically safe circuit so that even in case of a problem
no sparks are produced. The disadvantage of this variant is the slower data
transfer rate.