3 Remote-Monitoring Diagrams: Door Access Control, Master Stations, & RTUs

At DPS, we've been designing custom remote monitoring applications for decades. Here are 3 common applications that we've worked on repeatedly in that time. You'll probably find at least one of the useful for your company:

1) Monitoring cell towers, huts, and substations

These 3 types of remote sites are some of the most common locations that DPS clients monitor.

To determine which RTU is required, we first need to determine how many contact closures, analog channels, and relay outputs are needed. If you have other equipment (usually legacy) that can communicate via serial port, we also need to determine how many of those units will need to be monitored.

Most NetGuardian RTUs include at least one serial port, with support for RS-232 being the most common. RS-485 is also available.

Next, we need to determine what form of transport or communication is available at the site. The most common is LAN, but there are occasions where a cellular network is the only form of communication. That's where the our cell modem comes into play.

We manufacture small RTUs ranging from 2 discrete inputs (ex. NetGuardian LT G2) to large units with 80 discrete inputs (ex. NetGuardian 480). Most of DPS RTUs are 1 rack-unit in size (1.75" high) and can be mounted in a standard 19-inch or 23-inch equipment rack.

For other mounting scenarios, we also manufacture the NetGuardian DIN that can be DIN-mounted (hence the name).

2) Building Access System

DPS clients often like to control doors electronically using our Entry Control Units (ECU). The standard models connect to a NetGuardian RTU. The ECU LAN can be connected directly to your LAN network (again, the name makes sense).

When installing the ECU, we'll use one unit per door. You'll also have:

1. Door sensors
2. Keypads and/or proximity cards readers, plus proxy cards (or key fobs)
3. Motion detectors
4. Push-to-exit buttons

Push-to-exit buttons are optional. By deploying them, we'll know when the door has been opened, who entered, and when. If the door is broken into (forced open or otherwise defeated), you'll get a fast notification and a complete history log.

3) Using a TrapRelay for the fire department

In this example, we have a Distributed Antenna System (DAS) that outputs SNMP. We need to feed this protocol into our fire panel, which only accepts contact closures.

With the TrapRelay RTU, we'll send SNMP via LAN directly to the TrapRelay. This device then converts SNMP to contact closures. We can tie this into the fire panel. The most common units we make are 32-relay and 64-relay capacity. We also make smaller units with 8 relays or 4 relays.

This application (and most others) can use a centralized network management system. This NMS master can support various protocols like SNMP, Modbus, and ASCII (text) protocols.