RFC-1 Advanced Operation page 6.22
An example is the easiest way to illustrate how this works. Suppose the telemetry input on channel 01 is a
transmitter output power sample. An alarm is programmed to monitor channel 01 so that if the transmitter power
goes too high, the RFC-1 will adjust it down into limits.
The RFC-1 control relays are momentary activation, about one-half second. Depending on how the transmitter
control works, there is no guarantee that a single, brief relay closure will bring the transmitter power back into limits.
Without the 8-15 instruction, the RFC-1 will activate the action sequence normally. When the action sequence
completes, a new set of reference readings are taken. Keeping with the example, after the action sequence
completes the power will be lower but not necessarily in limits. When the new reference reading is made, the out-of-
tolerance condition will be considered normal on the next alarm check because the reference reading reflects the out-
of-tolerance condition. (If you are wondering why the system operates this way, consider what would happen if it did
not and you tried to shut your transmitter off. The non-stop phone calls would become annoying very quickly!)
The solution is to use the 8-15 instruction in the action sequence. The action sequence has the necessary relay
closure(s) to lower the transmitter power followed by the 8-15 instruction. The 8-15 instruction must be the final step.
When this action sequence executes, the relays operate and the reference reading update is skipped. On the next
alarm check, the current power reading is still out-of-tolerance. The action sequence will be triggered again and the
power will be lowered until it is back into limits.
In certain conditions it is necessary to have the RFC-1 treat an alarm as if the channel reading is within limits so that
the alarm will trigger as needed. Common uses for this behavior are transmitter power changes and tower light
monitoring. These instructions are typically used in conjunction with devices that operate at multiple levels and have
alarm limits associated with each level of operation. This implies that there are multiple alarms set up monitoring the
channel with the inappropriate alarms blocked during hours of the day in which they do not apply.
Setting up and blocking alarms is beyond the scope of this example. The next section of this documentation
discusses these topics. For this example it is only necessary to accept that multiple alarms can monitor the same
channel and alarms can be blocked during inappropriate hours of the day so that alarms do not conflict.
An example best illustrates use of these instructions. Suppose a transmitter is supposed drop to low power in the
evening. A power reading on channel 01 indicates at what power level the transmitter is operating. Two alarms in
the RFC-1 monitor this channel. One alarm is active during the day and has limits that are appropriate for daytime
power; it is blocked at night. The other alarm is active at night after the power change and has appropriate nighttime
power limits; it is blocked during the day.
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