Watchdog II Mesh User Manual
P/N 86-0006-00
Rev E 01-2020
Page
6 of 38
discrete inputs or the digital output can also be controlled independently. The setup of the digital output
is done through the website.
1.2.3
Pulse Counter / Accumulator Digital Input
Another dry contact input (Pins 6 and 9) on the Base Station can be used as a pulse counting
accumulator. A typical application would be to read an electric meter or a transfer station volume
counter. If the accumulator is used, it will occupy one of the 16 measurement channels that the Base
Station can monitor.
1.2.4
Analog Input (0-5 VDC or 4
– 20 mA)
An analog signal can also be monitored by the Base Station. Its analog input (J2, pins 7, 8, and 9) can
be set up to monitor a 4-20 mA two terminal device, a 4-20 mA three terminal device, or a 0-5V device.
The device is continuously monitored by the Base Station. Alarms conditions will be reported whenever
the analog input is outside of user defined alarm limits for a user defined amount of time. If the analog
signal input is used, it will occupy one of the 16 measurement channels that the Base Station can
monitor.
The Base Station can also monitor the DC power input. This is useful if the base station is powered by
a solar panel. The base station could monitor the actual voltage being supplied by the solar panel and
report that voltage to the website. If the DC power input is to be monitored, it will occupy one of the 16
measurement channels.
1.3 Data Communications
The function of the Base Station is to wirelessly collect voltage readings from the wireless modules and
local analog and digital inputs, determine if an alarm condition or periodic report condition exists, and
transmit the readings in short data packets to the Pipeline Watchdog website. Data can be transmitted
and received via an internal GSM digital cellular radio or an external Skywave Inmarsat satellite modem
terminal.
The Base Station implements two-way handshaking communications so that its transmissions are
positively acknowledged by the website, and vice versa. In the event the initiating end (the Base
Station or the website) does not receive an acknowledgement (ACK) from the receiving end, it will
attempt a retry after several minutes. If an ACK is still not received, a third and final retry will be
initiated several minutes later. This 3X redundant data packet transmit/ACK protocol makes the
WatchdogCP RMU system extremely robust from a communications standpoint.
The following communications options are available for the Watchdog II Base Station:
1.3.1
Digital Cellular
Digital cellular coverage is widespread throughout the world in urban and suburban areas and along
most highways. Its coverage footprint continues to grow. The major CDMA carrier in the US is
Verizon, GSM carriers in North America are AT&T and T-Mobile (plus Rogers in Canada and Telcel in
Mexico).
Elecsys’ GSM RMUs will work wherever GSM coverage exists in North America.
