12
5.4.1
Switching Analog Alarms to Current Operation
Adjustable jumpers on the NetGuardian circuit board
To test the analog alarm voltage/current jumpers, follow these steps:
1. Make sure the NetGuardian is powered down and disconnected from all network connections.
2. Remove the screws from the sides of the NetGuardian case.
3. Slide the top cover of the case off to expose the circuit board.
4. The adjustable jumpers are shown in the above diagram. All alarm inputs can be individually
configured for current or voltage operation. Remember that the default jumper position is OPEN
for measuring voltage.
Note:
Each jumper inserts a 250-ohm shunt resistor across the input.
This must be taken into account when defining the analog input reference scale.
+
Current
Voltage
+
Jumper installed for current
Jumper removed for voltag e
Unjumpered/Open Position:
Voltage Operation (default)
Jumpered/Closed Position:
Current Operation
4 to 20 mA
Current Source
Transducer
Voltage Source
Transducer
Analog
Channel
Input
-
-
Analog
Channel
Input
250 Ohm
Shunt
5. Slide the top cover of the case back into position and replace the screws.
6. Reconnect and power up the NetGuardian.
