Vaisala GMP251 - Relay Box Quick Guide; Overview

1. Relay Box Quick Guide
1.1 Overview
The GMP250 relay box allows using the analog current (mA) output channel of Vaisala
CARBOCAPâ Carbon Dioxide Probes GMP251 and GMP252 for relay control.
The voltage (V) output channel is not used for relay control with the relay box: the voltage
channel provides CO
2
measurement output (feedthrough via the relay box) in the same
manner as when wired directly without the relay box.
The relay
configuration (activation and release limits, error state output) is done using
GMP251/252 serial line interface commands.
Table 1 GMP250 Relay Box Specifications
Property Specification
Maximum switching voltage 50 VDC, 50 VAC
Maximum switching power 30 W, 30 VA
Number of relays 1
Probe output to relay • Current output to relay control: ppm CO
2
• Voltage output through the relay box: ppm CO
2
or
% CO
2
Probe power supply requirements 20 ... 30 VDC supplied through the relay box
Relay configuration interface Serial line (Vaisala Industrial Protocol)
Using GMP251/252 for relay control requires using the Vaisala Industrial Protocol serial line
interface to configure the probe to use relays, and wiring the probe to send output and
receive power through the relay box.
• For instructions on carrying out the serial line configuration, see Serial Line
Configuration (page 4).
• For wiring instructions, see Probe and Relay Box Wiring (page 10) .
This Quick Guide instructs how to carry out the serial line
configuration and wiring related
to using the current output for relay control. For more information on GMP251/252 serial
line commands and other functionalities, see the user documentation of the probes:
• GMP251 User Guide (M211799EN)
• GMP252 User Guide (M211897EN)
Chapter 1 – Relay Box Quick Guide
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