Monday, April 14, 2014

Sensatronics EM1 Environmental Sensor with PRTG

Monitoring the EM1 Sensor from PRTG
How we got here...

In the past we have had issues with the A/C in our computer room. The A/C unit was spec'd out with a consumer grade unit (Carrier) rather than a more traditional unit. Unfortunately the unit was not optioned to run in cold weather, and there were issues with charging the unit that required extra maintenance.

As so our locked room would occasionally have a propped-open door with a fan exhausting heat into the office. Of course we care about physical security, and the prospect of increased downtime when these failures occur on a weekend or during a vacation. So we looked around for a simple environmental monitor and came up with the Sensatronics EM1 (around $500) and Overseer software.

Overseer is designed to run on your workstation, which means leaving the machine running all weekend. Loading it up in a VM produces inconsistent notifications. And we also need to collect syslogs.

So, we are evaluating PRTG. PRTG loads up on top of Windows 2012 in a VM, does an auto discovery (here I blocked it from discovering desktops lest I get notified every time someone shuts down). And there is a Beta version syslog repository. Good start...

There is a monitor in our APC UPS which was discovered properly. But since we bought the EM1 monitor I figure let's give it a try. The EM1 has additional sensor capacity, and I could use it in a new location.

Key Tricks

Getting started - PRTG doesn't ship with the device information for the sensor built in, so auto discovery will not work. But, PRTG does have a concept of templates for the devices. And Sensatronics has a zip file of basic device configurations here. Update 7/2017: The zip file is no longer on Sensatronics' website, best option is to call support.

Load the extracted files into the program directory for PRTG on the server, in our case:
\\prtg\c$\Program Files (x86)\PRTG Network Monitor\devicetemplates

With the templates loaded we need to create the new device as follows:

In PRTG we need to do two things:
  1. Create a new group, (I called it SNMP V1) because the SNMP version is inherited from the group.
  2. For SNMP set the inheritance of settings OFF, and set the version to v1
Now we create a new device in PRTG, and specify as follows:

Start the discovery and you should get:

Which is at least data. The temperature is the main point, it's not 8 degrees in there. The web page on the sensor shows this:

And so here is where I call Sensatronics for Tech Support :-)
And.. the answer is, the template for the device has an error. In the column 'division' the entry should be changed from '10' to '1'. Do this in all the sensors. In my case I only have three sensors active.

And the result:

(Yes we do run hot. Saves energy.)

So there you have it. Thanks to Keith from Sensatronics for the final tip!


Unknown said...


I searched PRTG and EM1 and then found your web stie. you mention that PRTG require a config zip file to "communicate" with EM1. However, the download link is already dead. Do you know if there is another way to download the config file?

Thank you.

Rich Snow said...

Hello Qaulity Conrad,

You should try calling Sensatronics support. Their website has changed. I have updated the post to indicate the change. Good luck!