Relay Timers are used to automatically control relays for applications that might require failsafe control. For instance, controlling a relay using a standard relay control command may prove dangerous. Instead, timers can be used to explicitly specify the duration of time a relay should be activated. Using relay timer commands, users may tell a relay to turn on for 5 minutes. Should the computer fail to communicate with the controller after 5 minutes, the relay will automatically shut off. To extend this analogy, users may repeatedly tell a relay to turn on for 30 seconds. The relay will stay on as long as the timer command is sent within 30 seconds. If the computer stops sending the timer command, the relay will turn off after 30 seconds, acting as a failsafe switch to control loads that may be time sensitive.
ProXR controllers include 16 timers, each of which can have their own duration of time in Hours (HR) Minutes (MN) Seconds (SC). Each Timer can control any Relay (R) using numeric ordering (the first relay is relay 0). Two types of timers are supported, Duration and Pulse. A Duration timer is a timer that activates a relay for a duration of time, then turns the relay off once the time has expired. A pulse timer is a timer that pulses a relay only after the elapsed time has expired. Pulse timers are useful for automatic gate control or garage door opening applications. Duration timers are controlled using a (T) value of 50-65 as indicated in the table below. Pulse timers are activated using a (T) value of 70-85.
Timers are simulated in firmware, and may not be suitable for applications that require precision accuracy. Similarly, each timer shares the same time base, introducing a margin of error of 1 second when activating timers at random. Perhaps the biggest technical question we receive regarding timers is a simple misunderstanding between the (T) and (R) columns in the table below. All controllers are equipped with 16 timers, but different controllers are equipped with different numbers of physical relays. A timer and a relay are not equal, but it may be helpful to use equal values as you learn. For instance, always control the first relay with timer 0, the second relay with timer 1, etc.
For some users, a 32 channel relay controller may seem limited with only 16 timers. However, any of the 16 timers may be applied to any of the 32 relays. So as long as a timer is available (not active), it can be applied to any relay. If your application requires more than 16 timers to run simultaneously, then a second controller would be required.