Specifications

5
controllers used for interfacing the Model 554 Sensor with the
microprocessor sensor inputs.
1. Switches - The switches are permanently mounted to the ‘front’ PC
Board, referred to as the ‘Switch PC Board’.
2. Relays - The relays are removable and mounted in sockets (and
secured with plastic cable ties) on the ‘rear’ PC Board, referred to
as the ‘Relay PC Board’.
3. Sensor Input - The Sensor Input is the 5-pin DIN jack located in
the lower left corner of the ‘Switch PC Board’. The ETS Model 554
Sensor contains both a RTD Temperature Sensor and a
Temperature Compensated Relative Humidity Sensor. Both input
signals interface with the system through this jack.
The ETS Model 554 RH Sensor is plugged into this jack. The
Model 554 Sensor Head (Sensing Elements) should be in the 532
Chamber Environment. The sensor is held in place on the divider
wall with a ¾” NPT plastic liquid-tight fitting.
The input is configured at the factory to accept the signal from the
ETS Model 554 Humidity/Temperature Sensor. The Model 554
signals are both 0-1VDC, equaling 0-100% RH and 0-100 °C (32-
212°F), respectively.
4. Sensor Interface PC Board – The Sensor Interface PC Board is a
dual channel device used to convert the 0-1VDC outputs from the
Temperature and RH sensors into 0-50mVDC signals for input to
their respective microprocessor controllers. Each channel includes
a ZERO adjustment potentiometer and a SPAN adjustment
potentiometer. This PC Board should be calibrated every time the
Model 554 Sensor(s) is recalibrated.
To calibrate the Sensor Interface Board:
Equipment Required:
1. 0-1 VDC signal source.
2. Digital Volt Meter