VPFlowScope M probe
36
© 2016 Van Putten Instruments BV | MAN-VP-SMPR-UK | Revision:1600 | Date:23-03-2016
10
Electrical connections
Tip: Use a shielded cable of good quality to connect the meter. Connect shield to
safety ground on one point.
For portable, non-critical applications, a switched mode 12 V DC, 1A power adapter
may be used. Switched mode power supplies that are of poor quality, might affect the
accuracy.
NEVER USE AC POWER. THIS WILL VOID WARRANTY AND BRING PERMANENT
DAMAGE TO THE ELECTRONICS. THE INSTRUMENT MIGHT BE DAMAGED
BEYOND REPAIR.
CONNECT THE M12 CONNECTOR BEFORE POWERING UP THE INSTRUMENTS.
The VPFlowScope M probe main plug is a M12 5-pin connector which contains the power input, an
analogue output and a Modbus interface.
Pin
Signal
Wire color
1
+12...24 VDC
Brown
2
0 Volt
White
3
4..20 mA signal, active
Blue
4
RS485 A
Grey
5
RS485 B
Black
M12 5-pin female connector
Power supply
The input voltage is 12 to 24VDC. Make sure that the power supply is at least 12V at the connector.
Voltage drops will occur in long cables resulting in insufficient power. The display will notify you when
there is insufficient power on the device.
10.1
4..20mA
An advantage of a current loop is that the accuracy of the signal is not affected by voltage drop over
the line. Even if there is significant electrical resistance in the line, the current loop transmitter will
maintain the proper current, up to its maximum voltage capability. The live-zero represented by 4 mA
allows the receiving instrument to detect some failures of the loop. An analogue current loop can be
converted to a voltage input with a precision resistor.
The VPFlowScope M probe's output is an active, non- isolated linearized output. This means that the
+ wire is shared between power supply and the analogue output. A current will draw back from the
instrument to the power supply.
Cabling
3 wires are required to create a current loop. It is advised to use a shielded cable to prevent electrical
noise to affect the signal.
Ohm's law can be used to calculate the maximum distance. There are 2 parameters that needs to be
taken into account.
1. The voltage available is equal to the input voltage
2. The resistance depends on cable quality and length