External Process Variables - Fluke VIBGUARD IIoT Installation And Operation Manual

Installation and Operation

7.3 External process variables

External process variables are fed into the CMS as an analog or digital signal by a control system or by a controller.
They are potential-free when they are fed in. Process variables that can define an operating state and trigger dia-
gnostic measurements must always be available.
Notes
Process variables provided by a controller or a control system must be galvanically isolated and comply
with SELV specifications.
Buffers made by Phönix Contact, for example, are suitable for galvanic isolation. The designation of a sui-
table buffer is: MINI MCR-SL-UI-UI-NC.
This buffer is freely adjustable and can be galvanically isolated both as a current signal and as a voltage
signal. When using this buffer, all primary input signals (voltage or current) must be converted to the
secondary signal 1..5V. Otherwise, faulty measurements may be the result.
The analog inputs AI17 to AI20 are suitable for measuring current or voltage signals. Each of the inputs may be
selected. The internal load resistance of the current input is 100 ohm.
Setting the signal type
Process variables or signals from displacement sensors (±20mA or ±24V) can be fed in via the analog inputs AI17 to
AI20. You can set the signal type via a dip switch on the board, which can be reached via a small hole in the cover
plate.
To adjust the dip switch, proceed as follows:
Note
Sensitive components on the board!
Components can be damaged as a result of carelessness when taking action on the circuit board.
If necessary, use a lamp to illuminate the opening in the cover plate.
Remove the cover cap with a suitable tool (flathead screwdriver, tweezers, etc.).
l
Carefully slide the dip switch into the desired position. To this end, use a suitable pointed tool (needle, twee-
l
zers, etc.).
Put the cover cap back on.
l
34 Edition: 03.2019