Campbell Scientific DC1765 Cellular Telephone Modem - Manual (Page 6)

DC1765 CELLULAR PHONE PACKAGE
4
NOTE: When a program is downloaded to
a station that switches power to the
transceiver, communication will be broken
when the program is compiled and all ports
are set low . If the downloaded program
does not include the instructions to switch
on the transceiver, it will be necessary to
visit the site and reprogram the datalogger
before resuming cellular communication.
7. PROGRAMMING TO SWITCH
TRANSCEIVER POWER
Switching power to the transceiver allows the
datalogger to maintain a lower power budget by
limiting communication to predetermined times.
The transceiver must be switched on before it
can answer or call.
This section provides examples of datalogger
programming to switch power. If the power
supply is sufficient to power the cellular
transceiver continuously without switching, no
special programming is necessary.
7.1 POWERING ON FIXED INTERVALS
The simplest program switches power on at
specific times and off a fixed time later. This
can be accomplished with two Instructions.
Instruction 92 sets the port controlling the relay
high to turn the power on and a second
Instruction 92 sets the port low. In these
examples, control port 1 controls the relay.
The following program switches the transceiver
on at midnight for 15 minutes:
* 1 Table 1 Programs
01: 10 Sec. Execution Interval
01: P92 If time is
01: 0 minutes into a
02: 1440 minute interval
03: 41 Set high Port 1
02: P92 If time is
01: 15 minutes into a
02: 1440 minute interval
03: 51 Set low Port 1
With the transceiver on for 15 minutes following
midnight, TELCOM would be set to call
automatically once a day at 2 minutes after
midnight. In some areas there are discounts for
calls during off hours.
To allow contacting the station throughout the
day, the transceiver can be turned on for the
first 10 minutes of each hour:
01: P92 If time is
01: 0 minutes into a
02: 60 minute interval
03: 41 Set high Port 1
02: P 92 If time is
01: 10 minutes into a
02: 60 minute interval
03: 51 Set low Port 1
Or one might want to power the transceiver for
one hour at 10 a.m. and at 10 p.m.
01: P 92 If time is
01: 600 minutes into a
02: 720 minute interval
03: 41 Set high Port 1
02: P 92 If time is
01: 660 minutes into a
02: 720 minute interval
03: 51 Set low Port 1
Whatever the time that the program powers the
transceiver, the station must be called while the
transceiver is on; it cannot answer a call at
other times.
7.2 PROGRAM TO ALLOW EXTENDING ON
TIME
In the previous examples, communication time
is limited by the program. When the datalogger
switches off the power, communication is
broken and cannot be resumed until the next
time the transceiver is powered. When
monitoring current measurements is important,
the caller must be able to extend the time the
link is active.
The following datalogger program powers the
cellular transceiver for the first 5 minutes of
every half hour. Twenty-five minutes is the
longest one must wait before calling the station.
A 5 minute timer is used to determine when the
transceiver is switched off. Once GT or TERM
has established communication with the station,
the caller can set flag one high (press F1 in the
monitor or graph mode) to restart the timer and
extend the time the link will remain active. The
transceiver is switched off 5 minutes after the
last time flag one is set high.