APC AP9319 Environmental Monitoring Unit

Maria D. Stephens

Knowing what the environmental conditions are in your server rooms and closets is a good way to avoid system downtime and the costs associated with replacing heat damaged systems. With that in mind, here is a review of the American Power Conversion (you know – the UPS guys) AP9319 Environmental Monitoring Unit.

Table Of Contents

First Impressions:

The APC AP9319 arrives neatly packaged with a temperature/humidity probe, rack mounting kit, rubber feet for non-rack mount installations, a serial cable for programming, installation and quick start guide, IP configuration Wizard CD, a power brick and two different power cords for the brick.

All components are a block powdercoat finish, with an APC logo and serial port on the front of the unit, and ethernet port, power plug, two temperature/humidity probe ports, a beacon port, an alert port and two A-Bus ports on the back. Also located on the back is a small bus connector for normally open or closed contact switches.

The temperature probe is about 1/2 inch thick, and 1-1/2 by 2 inches in size, and connects to the monitor box via a 10 foot cable with a PS2 connector. The temperature probe can be easily mounted to a wall or rack with the included velcro tape strips.

The temperature / humidity probe that we are also testing is the same size and shape as the standard temperature probe.

Physical Installation:

The AP9319 is easy to install using any of several methods. The unit itself is fairly small, 1 RU tall, by about 4 inches deep and 6 inches wide. It comes with rubber feet if you just want to set it on a shelf, a small bracket with eyes for hanging it on a wall, and a short and a long rack ear for mounting in a 19" rack. The unit has an external power supply, which will need to be secured to something as it uses a barrel connection for power and doesn’t have any sort of power cable retainer. Installation took only about 5 minutes into both a Chatsworth rack and a Compaq server cabinet. There where no issues racking it in either cabinet.

The temperature / humidity probe comes with a circular piece of velcro for mounting. As the probe is extremely light weight, this is more than enough to hold it up. You could use cable ties to hold the probe to something, but I’d put the velcro behind it then too, just to make sure you have insulation from whatever you are mounting it too, and to allow for better airflow around the probe.

Deciding where to put the unit, you’ll need to take into account the 10 foot length of the cable attached to the probe. We mounted the unit into the empty top space of a rack full of routers and switch gear, with one probe attached to the top of that same rack, then installed a second probe into the top of a cabinet, and routed the cable back down the ladder racking to AP9319. We didn’t have a beacon or any probes other than the 2 temperature / humidity probes, so attachments to the back consisted of the 2 probes ps2 style connectors, the power barrel and an ethernet cable. Total time to install, including deciding where to put the probes and running the cables back to the unit was less than 20 minutes.


The APC offers several ways to do initial configuration. The included serial cable, APC Wizard Software, DHCP/BOOTP options or the way that I decided to try since I hadn’t done it before, via ARP and PING options. This is a well documented method that requires only knowledge of the MAC address of the unit and either a Windows or *nix box. I had no problems at all setting an IP address via ARP and PING, and quickly logged first into the telnet interface to the unit to make sure that it picked up the IP address, then into the Web interface for configuration for this review. One thing that was noticed right off the bat was that the unit didn’t allow me to login via the web interface as someone was already logged into the telnet interface.

For configuration, first things first. I permenantly set the IP address of the unit, and restart it in order to make sure that it took. Once that was done, I stepped through the initial options for connectivity. These include:

And of course user setup.

All of the configuration screens on the system are easy to manage, and follow the same APC web interface layout that many people are already familiar with. There are a couple of items in the setup configs that I’d like to point out.

1. Telnet/SSH – The system only allows Telnet or SSH. They can’t be running at the same time. The system also lets you select what port to use for either telnet or SSH. And the SSH options are nice, with the ability to select SSH v1 or v2, and the encryption algorithms that you’d like to use for each version. All the old standbys are there (3DES, Blowfish, AES 128 or 256).

When setting up SSH, you are prompted to agree to US Crypto Export rules before SSH will enable. Annoying but rules are rules. It’s a nice simple click, and you are done.

SSH also lets you use host keys for access. I didn’t test this functionality, but I understand from another engineer that it works very well.

2. SNMP. You don’t have a choice of SNMP version in the APC, or if you do I wasn’t able to find it. I am concerned that the system ships with SNMP enabled by default, using public or private, and allows open access to whoever finds the unit.

3. Email. Email configuration uses only a server and From email address. There is no ability for any other type of security, such as requiring authentication to send email.

4. Syslog setup is very nice. The system allows you to have up to four available syslog servers, and a nice mapping feature from the devices to syslog levels. Another nice touch that exists in many APC models is the ability to test your settings right from the settings page, such as the Syslog Test.

5. HTTP/SSL. Being a good security guy, I prefer that all my web servers be SSL enabled, and the APC makes it easy to do so. Once again you get the US Export warning. Much like telnet/ssh, you have the option to change the port that you are using for either HTTP or HTTPS, and can configure SSL with any number of options.

6. SSL/SSH Gotcha – If you configure the unit at one address, and generate the SSH and SSL keys internally, then change the units address, you won’t be able to connect to the unit at it’s new address. I recommend not configuring the keys until the unit has the address it’s going to keep.

As you can tell, there are a large number of settings available to you when configuring the AP9319. And we haven’t even gotten to the sensor configuration. More on that in the next section.


The AP9319 is a set it and forget it type device for the most part. Once the system has been configured and tested, you can deploy it and let it run, only paying attention to it when you get an alert, or need to change any of the config.

I wanted to touch on a couple of things here. First is the configuration of the sensor systems, which we haven’t covered yet, and the second is monitoring of the system.

You are given a very nice range of options when configuring the sensors on the AP9319. We tested the unit with the Black Temperature / Humidity sensors attached to the probe connectors only. No Alink testing was done. You can rename the sensors as you see fit – for example, you could call one Server_Cabinet and the other Network_Rack. You are also given a wide choice of settings for problems. The basics are setting the maximumn and minimum settings for temperature and humidity, then you can set fast rise, slow rise, fast fall and slow fall settings for both temperature and humidity, for each probe. In most server rooms a fast rise of 5 degrees in 30 minutes is a good setting – that will tell you quickly when your AC unit isn’t handling the load. Once you have those set, you can also associate responses from either the optional Beacon light or from the relay outputs for any event. That’s a nice touch.

As far as monitoring the device goes, you can do any number of things, ranging from not monitoring it at all, just watching for alerts, to monitoring the web page for any temp change on a 24/7 business. We use a middle ground and monitor that the unit is there from Nagios, and keep track of temperatures using MRTG/RRDTool. There are scripts for both setups easily found online, and they provide a nice touch for making sure you environment is safe as well. In the near future we’ll be testing the APC management appliance, so keep an eye out for that review.

Update: Turns out that the config for monitoring Temp and Humidity with MRTG isn’t as easily found online as I mentioned. The configs that I have found either don’t work correctly or require using an external PERL script. So to save everyone some time, here is a sample config that traces Temp as one variable, and Humidity as another, displaying the output in Celsius and %RH.

I haven’t had a chance to try the AP9319 with it yet, but there was a recent article in Sysadmin magazine about using a couple of small changes to Nagios to monitoring incoming SNMP traps. I use the setup for routers and switches, but I think that using it for monitoring the environment would be a nice touch.

The AP9319 also allows, via it’s Alink connectors, control or monitoring of an APC Air Removal Unit (for their racks). You also have the option of linking alarms to the output relay connectors, which can be easily mapped to alarms in the sensor configuration portion of the system.


Overall the AP9319 is a good closet monitoring tool. It has a good variety of options, allows for a decent selection of alerting options and can be monitored by a variety of applications, most of which are probably in use at most sites. Options for communications with the device are very nice, with good secure options including HTTPS and SSH. No secured SNMP however.

One downside of the AP9313 is the limitations on monitoring probes. The system only supports Temperature and Humidity probes, not the smoke sensor or water sensors that are available from APC. If you would like to or need to monitor anything other than temperature or humidity, you’ll need to look elsewhere.

viperlair.com gives the APC AP9319 Environmental Monitoring Unit a Good Rating. It does what it’s designed to do, and the only downsides are the lack of secure SNMP access, and the limitations on usable sensors. The AP9319 is otherwise perfect for deployment in small closets or server rooms, and a great addition to your network monitoring toolbox.

Featured Reviews

190,988 Reviews Analyzed
12,630 Reviews Analyzed
21,001 Reviews Analyzed
19,252 Reviews Analyzed
242,905 Reviews Analyzed
627,677 Reviews Analyzed
1,570 Reviews Analyzed
11,447 Reviews Analyzed
100 Reviews Analyzed

Related Posts

15 Best Competitor Monitoring Tools in 2023

In order to stay competitive in 2023, are you looking for the best competition monitoring tools? Look nowhere else! Our in-depth overview covers the best t...