4. Configure the current output channel's relay settings with the rsel command:
rsel [channel parameter release_ppm set_ppm release_value set_value
startup_value error_value]
• channel= analog output channel: set to 2 (current)
• parameter = the parameter that controls the relay: set to co2
• release_ppm = CO
2
ppm level at which the relay is released
• set_ppm = CO
2
ppm level at which the relay is activated
• release_value = the current output (mA) when the relay is released
• set_value = the current output (mA) when the relay is activated: set to 12
• startup_value = during probe start-up, if the CO
2
ppm level falls between the
release_ppm and set_ppm values, startup_value shows the state of the relay
(mA): the relay is either activated, released, or in error state.
• error_value = the current output when the probe is in error state
The relay mode of GMP251 and GMP252 probes has been designed to use 12 mA as
the relay control current. Use only 12 mA for the set_value configuration when
using the relay box with GMP251 and GMP252.
Example:
Set the analog output channel 2 (current) to control relay operation with the following
settings:
• The relay is activated when the measurement is over 10100 ppm CO
2
and released
when under 9900 ppm CO
2
. Setting these relay activation limits means using a
1 % CO
2
(10 000 ppm CO
2
) relay setpoint with a hysteresis of ±1 % (100 ppm CO
2
).
• The output current is 0 mA when the relay is released.
• The output current is 12 mA when the relay is activated.
• The output current is 12 mA if during probe start-up CO
2
ppm level is between 9900
and 10100 ppm.
• The output current is 0 mA when the probe is in error state.
Enter the following commands:
pass 1300
smode relay2
rsel 2 co2 9900 10100 0 12 12 0
Relay Box for GMP250 Carbon Dioxide Probes Quick Guide M211920EN-C
6
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