The Apollo Marine 55000-772MAR is a DIN-Rail Switch Monitor Plus, designed to monitor the state of one or more single pole, volt-free contacts that are connected to a single pair of cables and to report the status to Apollo compatible analogue control equipment. In addition, the 55000-772MAR incorporates additional circuitry to monitor flow switched and provide a time delay in doing so. The Apollo 55000-772MAR also contains circuitry which can be used to reset a beam detector.
The Apollo Marine DIN–Rail switch monitor provides four input states to the control equipment: ‘normal’, ‘fault’, ‘pre-alarm’ and ‘alarm’. The unit has a red LED to indicate an alarm and a yellow LED to indicate a fault condition.
The 55000-772MAR is loop-powered and operates at 17–28V DC with protocol voltage pulses of 5–9V. The unit is designed to accept a maximum line resistance of 50Ω. The end-of-line resistor required is 20kΩ.
