Honeywell CENTRA LINE MERLIN NX Series Installation & Commissioning Instructions page 23

MERLIN NX ROOM CONTROLLER – INSTALLATION & COMMISSIONING INSTRUCTIONS
Bias Resistors
Each universal input is equipped with one bias resistor. See
Fig. 29.
SENSOR
GND UI
R S2
DOWN
Fig. 29. Schematic of universal inputs and bias resistors
LEGEND:
V = 10 V (except for UI1-4 of RL8N, which have 24 V).
UP
R = Bias resistor (with a resistance of 24.9 kΩ in the
BIAS
case of NTC10kΩ and NTC20kΩ sensor inputs,
and 7.5 kΩ in the case of Pt1000 sensor inputs);
can be switched OFF via software by S1 to support
0...10 V inputs without bias current ("high
impedance") – except in the case of UI1-4 of
RL8N, which have a resistance of 11.8 kΩ and
cannot be switched OFF.
R = Series resistor for voltage dividing and filtering
SER
(with a resistance of 150 kΩ).
R = An internal load resistor (with a resistance of
DOWN
49 kΩ); depending upon the given type of con-
nected sensor, the firmware may switch this
resistor OFF.
Analog Outputs
The terminal blocks containing the controller's analog outputs
are green. Analog output types: See Table 5.
The analog outputs of the RLxN controllers (large housing)
are protected against voltages of max. 29 VAC and 30 VDC
(due to, e.g., miswiring).
NOTE: Connecting 24 VAC to any analog output of the
RSxN controller (small housing) will damage the
hardware.
S1
R
BIAS
V
R
SER
ADC
UP
23 EN1Z-1035GE51 R0420