Trumeter 877 Serie Manual Del Usario página 23

The base unit can be fitted with one or more of these optional circuit boards:
Relay, Analog Output or RS485 Serial Communication.
Relay option board
This contains two SPCO relays (see page 12).
Each relay has a programmable High Setpoint and Low Setpoint. The relay will operate
when the display reads higher than the High Setpoint or lower than the Low Setpoint.
Once a relay operates, it will not release until the reading returns back across the
setpoint, and then changes by a further amount. This amount can be programmed by
setting the Hysteresis parameter. This is a single programmable value that is common to
both relays and both setpoints.
Be careful not to overlap the hysteresis values, as the relay board will not work correctly.
Examples:
High Setpoint
Hysteresis
Display Reading
Hysteresis
Low Setpoint
Operate
Release
Hysteresis
Low Setpoint
High Setpoint
Hysteresis
Display Reading
Operate
Release
Relay
Relay
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