Vaisala PTB200 - Manual (Page 6)

PTB 200 5 (28)
Digital Barometers
SSD/Operating Manual 24th February 1993 PTB200-O0284-1.1
2.3 Power connections
Two wires, one for supply voltage and another for supply ground, are
needed to connect power to the barometer (see Fig. 3).
POWER JUMPER
ON
OFF
-
CTRL
+
normal use
external control
using CTRL line
Fig. 3 Power connections and jumpers
However, when a logic output is available in the host system, a third
wire can be connected to the power control terminal CTRL to enable
external control of the barometer. The POWER jumper of the barometer
must then be removed (see Fig. 3). The logic high TTL level (5 VDC)
turns the barometer on and logic LOW (0 VDC) turns it off. The CTRL
line can withstand higher logic voltage levels and is protected against
electric discharges. To return to normal operation simply re-insert the
POWER jumper.