Vaisala GMP 251 Quick Start Manual

Vaisala GMP 251/252 CO
The Vaisala GMP251 and GMP252 Carbon Dioxide probes are compatible with the
Nexsens X2 data logger using RS485 Modbus RTU output.
Note that the GMP25x sensor membrane and cable connection are NOT
waterproof. A waterproof, gas-permeable membrane must be installed on the
sensor and the green M12 cable connection must be waterproofed prior to
deployment.

Wiring

Note: Most sensors will have factory-installed UW connectors. If this is the case,
skip to the Configuring the Vaisala GMP 251/252 section.
For compatibility, a Vaisala sensor cable must be fitted with a NexSens UW
connector to interface with the X2 data logger.
For user-wiring with a NexSens UW-Field Wireable Plug (UW-FWP) follow the wiring
diagram below.
Vaisala 223263SP Cable
Wire Color
Brown
Blue
White
Black
Configuring the Vaisala GMP 251/252
Note: All GMP25x sensors not integrated by NexSens technology require the use of
a PC terminal connection and Vaisala's USB interface cable to modify the sensor
output.
1. Download or launch a terminal emulation software. NexSens recommends
Tera Term as a free open-source option.
2. Connect the Vaisala USB cable and verify Windows properly downloads the
necessary drivers automatically. Verify this appears as a unique COM port
connection in Window's Device Manager.
Quick Start Guide
Sensor
Signal
12 to 30 VDC Power
Power GND
RS485-B
RS485-A
1
Probe
2
UW-FWP J Pin
Connection
J5
J2
J7
J8
2091 Exchange Court
Fairborn, Ohio 45324
937-426-2703
www.NexSens.com