RFC-1 Advanced Operation page 6.29
6.6.7 Blocking Alarms by Time
It is possible to disable a telemetry alarm during certain hours of the day by programming an alarm block. Alarm
blocks are used in cases where an alarm is not valid during part of the day. Tower light monitoring is a good
example. Tower lights are typically not on during daylight hours so an alarm monitoring tower light power can be
blocked to prevent a false alarm.
Alarm blocks use the same memory area that date/time triggers use—memory addresses 0256-0639. An alarm
block is a special programming case and the RFC-1 will recognize it as an alarm block instead of a date/time trigger.
Date/time triggers are discussed in the next section. It is not necessary to know how they work yet. Alarm blocks
share the memory space. A sample selection from the programming address table will help illustrate this.
- Programming -
Addr Description Section Default Current Alternate Use / Notes
0256 Date/time trigger 48: action sequence 6.7.4 0 ____ Alarm block 48: block indicator
0257 Date/time trigger 48: month 6.7.4 0 ____ Alarm block 48: alarm to block
0258 Date/time trigger 48: date—value 1 6.7.4 0 ____ Alarm block 48: month
0259 Date/time trigger 48: date—value 2 6.7.4 0 ____ Alarm block 48: day(s) of week
0260 Date/time trigger 48: hour—value 1 6.7.4 0 ____ Alarm block 48: start hour—V1
0261 Date/time trigger 48: hour—value 2 6.7.4 0 ____ Alarm block 48: start hour—V2
0262 Date/time trigger 48: minute—value 1 6.7.4 0 ____ Alarm block 48: end hour—V1
0263 Date/time trigger 48: minute—value 2 6.7.4 0 ____ Alarm block 48: end hour—V2
The listing above shows how the alarm block data uses the date/time trigger memory. Look specifically at the column
labeled Alternate Use. It describes the alarm block.
• The first memory address is always programmed to 15 for an alarm block.
• The second memory address identifies the alarm (A-H) to block using numbers 1-8 respectively.
• The third memory location identifies the month (1-12 or 15) in which to activate the block.
• The fourth memory location identifies the day of week (1-7 or 13-15) on which to activate the block.
• The fifth and sixth memory locations store the start time (hour) of the alarm block.
• The seventh and eighth memory locations store the end time (hour) of the alarm block.
Always program a 15 in the first memory location to indicate to the RFC-1 that this is an alarm block and not a
date/time trigger.
For the alarm to block, use numbers 1-8 to represent alarms A-H where: 1=A, 2=B, 3=C, 4=D, 5=E, 6=F, 7=G, 8=H.
An alarm block can be active every month or during only a specific month. Use numbers 1-12 to represent the
months January - December respectively. Program the value 15 if the block should be active every month.
An alarm block can be active every day of the week, a specific day of the week, weekdays only or weekends only.
Use numbers 1-7 to represent the days of the week where: 1=Monday, 2=Tuesday, 3=Wednesday, 4=Thursday,
5=Friday, 6=Saturday, 7=Sunday. Extra day of the week values are: 13=every weekday (Monday-Friday),
14=weekend days (Saturday & Sunday), 15=every day of the week.
The start hour and stop hour define the hours of the day that the block will be active. When a block is active, the
specified alarm does not occur—it is blocked. Alarm blocks start and stop on the hour—there are not enough
memory address in the group to store hours and minutes. Alarm block hours are programmed using a 24-hour clock.
The block time can cross midnight.
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