Appendix C. CS700H Operation Details
C-3
When snow is last detected, a timer is left running to keep the heater cycling so
that any snow built up on the funnel will be melted. The
Snow Run-on
timer is
factory preset to 18 minutes but may be extended as required.
The heater will cycle on and off for the
Run-on
time or while ever snow is
detected (see FIGURE
FIGURE C-3. Diagram showing how the “Snow Run-On” timer controls
the heater.
C.1 High Power Operation
If the snow sensor is disabled (
a
X22!
command set to
0
), the heater will cycle
continually when the ambient temperature falls below the
Active On
temperature (
a
X23!
command) and is above the
Low Off Temperature
(
a
X25!
command). This assumes the system is active. Because this mode
consumes more power, high power operation is only recommended when the
CS700H uses AC power.
C.2 External Control
The CS700H is set to by default to
Automatic control
– where the CS700H
monitors the ambient temperature and the snow sensor and operates the heater
automatically. Data loggers in weather stations that monitor the ambient
temperature and the snowfall can control the tipping bucket heaters directly.
Set the
a
X20!
command to
1
for
External Control
, and then use the
a
X29!
command to enable the heaters to cycle on/off (=1) or disable the cycling (=0).
The ambient temperature, block temperature, snow sensor and state of the
heaters can be measured using the
a
M!
,
a
R!,
or
a
C!
command, as normal.
The
Setpoint Temperature
is the required temperature of the
funnel – and not the block temperature read from
a
M!
and
a
R!
commands. The relationship between the funnel temperature,
block temperature and ambient temperature has been determined
through extensive testing.
There is an alternate external control mode, whereby the controlling system can
actually turn the heating elements on and off. This is done using the
a
X21
!
command, with heater on (=1) and heater off (=0).
NOTE
