What is a PGM output on a DSC PC1616, DSC PC1832, and DSC PC1864?
A very common question we get with people looking at buying DSC PowerSeries or from those at already have one is: "What is a PGM?" First PGM stands for 'programmable output'. So a PGM is a programmable negative trigger output. What does this mean? You can think of a PGM as an on/off switch like a light switch. It will be connected to something to provide power that can be turned on or off. The system will flip the switch based on what PGM type you program it for. It is the negative side of the direct current circuit. The other side will generally be on the positive auxiliary power terminal.
Different PGM outputs will have different current draw limits. The most common that you will encounter are the two or four PGM's on the main PowerSeries panel. The PC1616 and PC1832 both have 2 PGM outputs. The PC1864 will have 4 PGM outputs. PGM's 1, 3, and 4 all are limited to 50mA each. PGM 2 is limited to 300mA. There are 2 modules available that can expand your PGM capabilities: PC5204 and PC5208.
A PGM can be used for countless applications including custom integrations with things like lights or garage doors. The possibilities are really pretty much endless. This especially true if you factor in connecting to relays and other power supplies. Much of the integration that is possible is really beyond the scope of what the vast majority of people will need and beyond what we will get into. In fact, many people will never need to use a PGM output on their system at all. There are a few very common uses for a PGM though that we will take a closer look at.
The most common use for a PGM is with smoke detectors. Smoke detectors are a latching alarm. This means that they will stay in the alarm state until their power is shut off. So if you ever get a smoke alarm, whether from testing or false alarms or real alarms, you will need to reset the power on the smoke detectors to take them out of their alarm state. There are two kinds of smoke detectors that you can use: 2-wire and 4-wire. With 2-wire smoke detectors, the PGM becomes the fire zone for triggering an alarm as well as the resettable power circuit for the devices. 2-wire smoke detectors must be used with PGM 2 on the main board to function. And PGM 2 must be programmed as PGM type 04. With 4-wire smoke detectors the initiating circuit is separate from the power circuit. So the PGM will only be used for the resettable power source to the 4-wire smoke detectors. Any PGM can be used for 4-wire smoke detectors since it is not also the fire zone. But you will want to keep in mind the total power draw that you have connected to the PGM to make sure that you are not going to be exceeding it. The PGM type that will need to be used with 4-wire smoke detectors is 03 for sensor reset.
Another common use is to use PGM's to turn on additional sirens or strobes. Generally the PGM will not be used to directly power the sirens or strobes in this case. Instead the PGM will be connected to a relay. The relay will be connected into a circuit with a power supply and the sirens or strobes. The relay should be connected in the normally open state so that the power circuit is not closed until the relay flips. The PGM would then trigger the relay to flip to the closed state when an alarm goes off which in turn causes the power circuit to be completed. There are multiple PGM types that may be used for an application like this depending on how you want it to function.
PGM definitions allow for numerous ways that the PGM will function. They can follow the bell output, follow zones, follow keypad chimes, 2-wire smoke zone, resettable power, et cetera. For a full list of PGM definitions check the full installation manual. In addition to the various definitions, there are are also attributes that can further customize those PGM types even further.