Different Ports for Different Sensors

The RTU has different types of ports to work with different sensors and requirements.  Input ports include contact closure (Digital), analog, and temperature ports.  Output ports include relay outputs and contact closure (Digital) ports.  Virtual ports are controlled by the RTU's Rules script.

Contact Closure (Digital) Ports

Contact closures can be configured (by software command or the front panel) to act as contact closure input ports or open drain output ports.  They are designed to work with the large range of equipment with contact closure alarm outputs, as well as other simpler devices such as "Door Open" alarm sensors.

Digital inputs are used for equipment alarm monitoring, tallies, and general equipment feedback.

Digital ports configured as outputs can be used to remotely switch devices on and off.

Latched Relay Output Ports

The contact closure ports described above can be soft-switched to act as either inputs or outputs.  Latched relay ports however can only be used as outputs.  They are hard wired voltage free switched relay output ports.  These relays retain their state even if power to the RTU is lost.

Analog Input Ports

Each analog input port can individually measure either direct DC voltage, or 4-20mA current.  You change the input type of the port by using a switch that is inside the box.  Each port has its own switch.

The 4-20mA input was designed to allow the RTU to use the hundreds of sensors available off the shelf that give out 4-20mA current readings.  These include such things as humidity, temperature, pressure, etc.

The other method used to measure analog readings is by voltage differential.  This allows a source of 0-60V DC to be measured directly, which is useful for direct voltage devices such as batteries.  The high common mode of these inputs allows batteries in series to be measured individually.

Temperature Input Port

Each RTU comes with two temperature sensors.  The internal sensor gives a digital reading of the temperature inside the RTU.  The external sensor can be placed away from the RTU to measure the ambient temperature.

Virtual Ports

Virtual ports are controlled by the scripting language embedded in the RTU.  The script allows you to write simple rules that can trigger alarms or activate outputs.  Virtual ports can be configured as inputs or as outputs individually.

 A virtual port configured for input is used to raise alarms from the script, and to act as a timer for some actions.

A virtual port configured for output can be used to trigger multiple actions.