Measurement Consumption
ASCII RS-232 Data
transmis
sion
Adds 1 ... 2 mA to the standby consumption during the message sending time. Note
that the host device's input (data logger or PC) can constantly draw some current
from the TX line.
RS-485 and RS-422
Data in
terfaces
Consume about the same amount of power as RS-232. With long data cables the
data consumption during data transmission can be much higher, especially when
termination resistors are used. On the other hand, the RS-485 driver is in high
impedance state when not transmitter. In idle state, no current can be drawn by the
host input.
NMEA modes They consume about the same as ASCII modes.
SDI-12 Native mode M=S, C=1 has the lowest stand by consumption, about 0.1 mA. Note that it can also
be used with RS-23
2 terminals. See the SDI-12 connection diagram in 5.5 Data
Communication Interfaces (page 67). In this case, the commands must be in
SDI-12 format, but no special line break signals are required. The SDI-12 mode is for
polling only.
SDI-12 Continuous mode M=R consumes about the same as the ASCII RS-232 mode.
If the optional sensor heating is enabled, SDI-12 Native mode consumes the same as ASCII
RS-232 mode.
When heating is on (or the temperature is such that it should be on), some 0.08 mA
additional current is drawn from the operational power supply.
While in Service mode and/or while supplied through the service port the transmitter
consumes
0.3 ... 0.6 mA more than in normal mode, when supplied through the
main port (M12 connector or screw terminals). When supplied through the service port the
minimum voltage level for reliable operation is 6 V. This can also be seen in the supply
voltage reading of the Supervisor message - the Vs value is 1 V lower than the actual input
voltage.
5.3 Wiring with 8-pin M12 Connector
5.3.1
External Wiring
The 8-pin M12 connector is located on the bottom of the transmitter.
WXT530 Series User Guide M211840EN-D
58
sales@streamlinemeasurement.co.uk
www.streamlinemeasurement.co.uk
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