Choosing The Right Remote Telemetry Unit (RTU) For Your Remote Alarm Monitoring And Control System

Selecting the right RTU for your remote sites can be overwhelming. When you're trying to find the right balance of capacity, interface, and features - how do you know what you really want?

Before you decide on an RTU, you should consider both its short-term and long-term effect on your network monitoring strategy. You want an RTU that will both immediately improve your network visibility and support your overall upgrade plan to support your future monitoring goals. Here is a quick evaluation guide for Selecting an RTU.

RTU Site survey

Your first step to get your alarm monitoring upgrade rolling is a complete survey of your current network and remote sites. This survey will document your existing alarm monitoring situation, in order to build a road map for your upgrade. This can be a bit tricky if you are starting from the ground up.

Current Network Monitoring Equipment Inventory:

You may think that adding a new RTU requires a completely new alarm monitoring system, but that's not necessarily true. Before you shop around, take an inventory of your current network monitoring equipment. You want to select an RTU that not only meets your current requirements but is also compatible with your existing network transport.

Here are some questions that will help you start your network-monitoring inventory:

  • How many remote sites need to be monitored?
  • What is the protocol and transport of the RTUs you're currently using?
  • How many alarm points do you need to monitor at each site?
  • How much rack space do you currently have available?
  • What dedicated facilities do you already have in place to transport RTU data?
  • How many ASCII devices (e.g., switches, routers, etc.) will you monitor at your remote sites?
  • What type of power do you have at the master and remote sites?

RTU Features

Before you select an RTU, think about what your ultimate goals are for your network monitoring.

Here are some questions that will help you form your future network monitoring plans:

  • How many alarm points will your network alarm system monitor in the next 5-10 years?
  • What alarm monitoring features will you need - discrete alarms, analog alarms, controls, serial ports, local visibility?
  • What kind of data transport do you want to use, now and in the future - overhead channels, terminal servers, LAN/WAN, other?
  • What protocols will your remotes use? Are you planning to shift your monitoring to a standard protocol like SNMP?
  • How do you want to mount your RTUs? (23" rack, 19" rack, wall, tabletop)
  • What type of alarm termination will work best for you?
  • Do you want to receive alarm notifications via email or pager?

Select an RTU for both Your Immediate and Future Needs

Once you've defined your current and long-term network monitoring goals, choose an RTU that meets your present needs and will expand to meet your future needs.

When you're planning your alarm monitoring, always think about the future. You don't want to get locked into an RTU alarm system that's inadequate for your future needs, but you also don't want to spend too much for alarm capacity you won't immediately use, either. After all, it's easier and more cost-effective to add alarm capacity in a controlled way in the near future than to rush a new deployment when you've exceeded your alarm capacity. Features such as an RTU with multi-generational hardware will ensure that your equipment can grow with your needs.

What RTU Features Do You Need?

Now that we have taken a look at some of the most important factors involved in deciding which RTU to choose, let's take a look at some essential features that any high- quality RTU will offer.

RTU Essentials

Here's a handy list of essential functions you should look for in an RTU. If a device cannot meet these basic requirements, cross it off your list.

Key alarm presentation and notification functions:

Pager and e-mail notifications:
Pager and e-mail notifications let your field techs respond to alarms while they're still in the field, speeding repairs and reducing windshield time. Look for an RTU with SMS support, which can send detailed alarm notifications to alpha pagers, cell phones, and PDAs.

Detailed alarm notifications:
Summary "major/minor" alarms don't give you enough information to make dispatch decisions. Look for an RTU that include detailed diagnostic information in each alarm.

Alarm correction instructions:
Detailed instructions included in alarm notifications ensure that system operators, without extra training, will know precisely what to do and who to call if an alarm happens.

Web interface:
Everybody knows how to use a Web browser. A Web interface makes sure all your field techs can access your RTU, from any computer and any location.

Essential alarm sorting and analysis functions:

Alarm sorting:
A large, complex network can create a cascade of alarms. Some are unimportant, but others are critical. Look for a RTU that can automatically sort and prioritize this flood of information for you.

Nuisance alarm filtering:
Even the best NOC staff stops taking alarms seriously if they're bombarded with status alerts, oscillating conditions, and unimportant alarms. Look for an RTU that filters these out.

Custom combination alarms:
A low battery isn't a serious problem, and neither is a failed generator - but they're pretty serious when they happen at the same time. Look for an RTU that can watch many different alarm inputs and spot critical alarm combinations.

Root cause analysis:
Finding the underlying cause between alarm cascades can take hours of patient detective work. Look for a RTU system that can automatically correlate repeated combinations of alarms.

History and trend analysis:
Identify problem areas and eliminate recurring problems with a RTU system that keeps a complete alarm history that's exportable for trend analysis.

Critical alarm collection and device management functions

Live analog monitoring:
You can't adequately monitor battery levels, temperature, and humidity with one-threshold contact closures. Look for an RTU that support for analog inputs, including live monitoring of actual analog values.

Control relays:
Many common site problems, from power outages to high temperature alarms, can be solved by quickly turning on a generator or an air conditioner. Remote operation of site devices is the best way to eliminate unnecessary site visits and it's a lot faster than going in the truck.

SNMP support and ping alarms:
If you're responsible for both telecom and IP equipment, consolidate all your monitoring on one RTU.

RTU Transport: Getting Your Alarms from the Site to Your Screen

Another very important factor to take into consideration when deciding upon an RTU is looking at how alarms will be transported back to your control office.

Once alarm data has collected at your remote sites, it needs to be transmitted over a data network to your alarm presentation master at your NOC. Alarm data can be sent over nearly any kind of data transport: Ethernet LAN/WAN, dial-up modem, dedicated circuit, overhead channel, WiFi, etc.

There are two things you should keep in mind about RTU alarm data transport:

  • As much as possible, you want to work with transports that are already available in your network. You don't want to create added expenses by committing yourself to installing new network infrastructure. It's best to choose an RTU that is compatible with the transport you already have.
  • It's a good idea to have a secondary backup path for your alarm data in case your primary path fails. No transport is 100% reliable, and you don't want to lose alarm visibility of your revenue-generating network under any circumstances.

RTU Sizing: Monitoring your small, medium and large remote sites

It is also important to note that the size of your network will determine the needs and requirements of your RTU:

Small RTUs:
Select a small remote alarm unit like the NetGuardian 216 for cell towers, remote huts, or enclosed cabinets (16 discrete alarms, 2 analog alarms, SNMP)

Medium RTUs:
Select a medium remote alarm unit like the NetGuardian 832A for remote switches (32 discrete alarms, expandable to 176 discrete inputs, 32 ping alarms, 8 analog alarms, 8 control relays, 8 serial terminal server ports, SNMP)

Large RTUs:
For central offices or regional hubs, select a large remote alarm unit like the modular Advanced Telemetry System (scalable from 96 to 1,824 discrete alarms, 48 to 864 analog alarms, 32 to 576 controls, SNMP or TL1)

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