Geist Watchdog 100 - Manual (Page 20)

GM1118 - Watchdog 100 Series User Manual 20 Revision Date: 2/16/2015
Sensors
Overview
All internal sensors are measured every 5 seconds. External sensors are measured every 10 to
30 seconds, depending on the number of devices connected. Sensor data collected by Watchdog
100 units provides useful trend analysis data. While all values are not absolute in relation to a
known unit, trend analysis of the data allows users to view changes and draw useful conclusions
about what is happening over time in the monitored environment.
Internal Sensors
Watchdog 100 units contain the following onboard sensors:
 Temperature: Measures temperature and can be displayed in °C or °F. The accuracy is ±1
°F from -50 °F to 185 °F. Note: This sensor may be heated by internal circuitry in the unit;
a temperature offset is available to re-calibrate.
 Humidity: Measures the percent of water vapor in the air within ±5%.
 Dew Point: Calculated measurement of temperature at which moisture in the air will turn to
water based on the humidity and temperature measurements.
 AI1: Scales 0 to 5 Vdc input to 0-99, dry contacts may be used.
 AI2: Scales 0 to 5 Vdc input to 0-99, dry contacts may be used.
 AI3: Scales 0 to 5 Vdc input to 0-99, dry contacts may be used.
 AI4: Scales 0 to 5 Vdc input to 0-99, dry contacts may be used.
I/O Sensors
The Watchdog 100 units come equipped with four I/O ports for connecting additional external
sensors such as Water and Door Sensors. The four ports are designed to accept a 0-5 Vdc analog
input; alternatively, an internal 100K pull up resistor to 5 V allows for the use of dry contacts.
The I/O port input is converted to a digital number ranging from 0 to 99 and is displayed on the
Sensors page. Unused I/O ports will display a value of 99. This range can be adjusted on the
display page allowing the user to modify the value to make it more meaningful to the user.
Water sensors act as conductivity bridges. Moisture across the contacts causes the value to drop.
Door switches can be wired in a serial connection; if the chain is broken the entire group is
classified as open. The limiting factor on the I/O ports is the length of the wire, found to be
around 400 feet.
Figure 20: Water Sensor Wiring Example