Where controllers are used, engineers often need multiple outputs to occur simultaneously with alarms. This is generally achieved using the 2-4 alarm outputs that come with controllers, plus an indicator with alarms. By contrast, Yokogawa's UT550/551 Digital Indicating Controller can output up to 8 alarms from the main unit alone.

The instrument has a total of 8 alarm outputs: 3 relay outputs (common); 4 transistor (open collector) outputs (common); and an additional 1 relay output if universal control output was not selected.

Of course, 8 alarm types and alarm settings can be set independently. There are basically 24 alarm types available. These naturally include upper limit, lower limit, and deviation alarms, but also include a wide variety such as alarm to idle mode or OUT value, alarm on time-up with the timer function, and alarm upon failure diagnosis/FAIL.

The instrument supports selective application of alarms, such as "always ON," "OFF when operation paused," or "OFF during manual operation." These are available through various option-enhanced models of the UT550/551 (which support 8 outputs). (-x1, -x3)