PA 358
Technical description Chapter 8
32
8.6 Operating
the
board
Base address
Adjust the base address of the board. Depending on the version, the board occupies
8, 12 or 16 bytes.
Watchdog
If you use the watchdog, jumper-select the watchdog time through J23
(5 ms, 500 ms, 5s ).
Be attentive to the fact that for triggering
Base a0
or
+4/+8/+12
have to be
written within the defined time.
The watchdog circuit is enabled through jumper J24. If you work with the watchdog,
then you cannot debug per software, as in this case no triggering is possible within
the necessary time interval.
Description of a task
In a chemical process, four control circuits are to be supervised and positioned
per PC:
Fig. 8-4: Description of the task
The PID controllers are analog controllers.
The predetermined value is set via a 4-20mA current loop;
it is possible to read it back.
The actual value is connected to the PID controllers with a 4-20mA current loop, it is
also to be supervised and recorded in order to obtain a daily production report.
Alarms can also be set via PC, so that an electric hooter sounds if the limit values are
exceeded.
With the
PA 358
board, you can control up to eight current loops.
With the
PA 302-16
board, you can write in up to eight current loops
(Differential mode).
The tasks is realized as follows:
One
PA 302-16
board with the option DC (Differencial Current)
One
PA 358-4C
board with the option Current Output (Channel 0 to 3)
One
PA 1500
board with 16 in- / 16 outputs 24V, optically isolated, to control the
relay, electric hooter, etc....