ifm
Basic Device Manual AS-i ControllerE M4 Target V15
2015-10-30
Terms and abbreviations
Hardware error, exception error
275
Polling
The controller master gets the data from every participant in the system one after
the other:
1. Master calls participant 1
2. Participant 1 responds with its current data (current 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 all other participants.
Cyclic 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 10 ms.
Profibus
Fieldbus system for larger data volumes, requires special cables, complex
connection technology. Different variants are available:
→Profibus FMS, DP or
PA. Profibus DP can be used e.g. as a supplier for AS-i over longer distances.
Corresponding
→gateways are available.
Profibus FMS
Profibus FMS (
F
ieldbus
M
essage
S
pecification) to network controllers - no
longer standardised as from 2007
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 PA
Profibus PA (
P
rocess-
A
utomation) is used to control field devices by means of a
process control system in process technology. This PROFIBUS variant is
suitable for hazardous areas (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
transmission rate.
Remanent
Remanent data is protected against data loss in case of power failure.
The operating system for example automatically copies the remanent data to a
flash memory as soon as the voltage supply falls below a critical value. If the
voltage supply is available again, the operating system loads the remanent data
back to the RAM memory.
The data in the RAM memory of a controller, however, is volatile and normally
lost in case of power failure.
RTS
RTS =
R
un
T
ime
S
ystem
Runtime systems are basic versions of applications. These minimum versions
are supplied with certain products to meet the prerequisites for the execution of
the actual product or to be able to look at or use results generated by this
product on other processors: Making available all routines required to execute a
program in a programming language, e.g. interactions with the operating system,
memory requirements, error routines, inputs and outputs.
