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HPM-2002-OBEVacuum Gauge Page 21 of 39
3.3.9. Modular Connector Pinout (R2-232) RJ-11 connector on left side.
Pin #1 .............................................................................. Ready to receive (output signal from OBE)
Pin #2 .......................................................................................................... Data (output from OBE)
Pin #3 and #4 ....................................................................................... Common Ground Reference
Pin #5 ................................................................................................................. Data (input to OBE)
Pin #6 .......................................................................................... Clear to send (input signal to OBE)
A common application of the RS232 version of the HPM-2002-OBE is to connect the pressure gauge
directly to the serial port of a PC. This is done by first wiring the supplied communication cable in the manner
shown below:
3.3.10. Modular Connector Pinout (RS-485)
The two RJ-11 Connectors are “Feed Thru” connections, since they are wired in parallel (see above fig.).
RS 485 half duplex RS 485 full duplex
Pin #1 T+/R+ Pin #1 T+
Pin #2 T-/R- Pin #2 T-
Pin #3 GND Pin #3 GND
Pin #4 GND Pin #4 GND
Pin #5 n/a Pin #5 R-
Pin #6 n/a Pin #6 R+
3.3.11. High and Low Set Point Modes
The HPM-2002-OBE provides TTL outputs for process control. These signals are available on the 15-pin
connector (see previous table in Section 2.4).
The High set point can be viewed using either the display or the serial connection. To view the high
setpoint, place the HPM-2002-OBE in the High mode by pressing the Select button until the High light (on the
mode bar) is illuminated. The display then shows the set point selected. During normal operation the alarm
light will illuminate and the TTL output (pin # 1) will go high (+5V) if the pressure exceeds the set point. To
view the setpoint using the serial connection, send “H<CR>”.
Similarly, to view the Low set point, place the HPM-2002-OBE in the Low mode by pressing the SELECT
button until the Low light (on the mode bar) is illuminated. The display then shows the set point selected.