Sensor Power Supervision parameter ()DI840 if True will hard wire signal on channel1 and 8 be ignored?
IF Sensor power supervision parameter true then channel 1 and 8 connected boolIO variables in control builder will show power in on or off?
CB Help not clear: This parameter enables/disables of the supply (L1+) to the input channels and transducer over current.If an error occurs the status of the unit is updated and the channel status bits will b
e set. The parameter can be set to True or False
From the help:
True: short circuit and open wire supervision is enabled.
These errors will be reported as External Channel Error
The supervision can be enabled/disabled per module (not channel vise)
From my experience: it is valid only for NAMUR (don't know exactly this standard) and with external resistor for cable supervision. If you use it with internal shunt and inductive sensor for example, it gives error each time when the circuit is open (no signal from the sensor).
Input thresholds, 12V / 24 V and external shunt (used for line supervision):
Open wire: 0 V ≤ VIN < 0.1 V
Contact open: 0.1 V < VIN < 1.6 V
Contact closed: 1.6 V < VIN < 6.0 V
Short circuit: VIN > 6.0 V
Sensor power supervision is for monitoring the field power(like L1+(1-8ch) and L2+(9-16 ch) connected to MTU) means whether you need warning(W will Lit) on the card when the power is disconneted from MTU.
If you disable this paramter u won't come to know on the card level whether the power is disconnected or not, You will come to know only by checking the voltage levels.
So its better to keep the sensor power supervision always enabled.