TEMPer Thermal Sensor

The TEMPer is an affordable (starting at under $20) USB digital thermometer that accurately senses temperatures from -55 to +125 degrees Celsius / -67 to +257 degrees Fahrenheit. This is an ideal addition to the server room to generate alerts should temperatures fall outside a safe threshold.

TEMPer devices work on all NEMS Linux hardware platforms. It will also work on the NEMS Linux virtual appliance, however you must connect the hardware to the virtual machine, which is beyond the scope of this documentation (please refer to the documentation for your hypervisor).

check_temper supports Critical and Warning states for both low (cold) and high (hot) temperatures.

Note

For optimum accuracy, it is recommended to plug your TEMPer device into a short USB extension cord so the thermal data isn’t impacted by the heat pulled from the USB port of your NEMS Server.

Setting up check_temper

Simply add check_temper_temp or check_temper_hum as a service to your NEMS host, having connected the TEMPer device to your NEMS Server’s USB port. You may specify your temperature thresholds in either degrees Celsius or Fahrenheit. NEMS will automatically determine which you are using.

Sample check commands are already included in NEMS Linux 1.5.2+ in the demo config. If you’re deploying a new NEMS Server, simply plug in your TEMPer device and these checks will automatically detect it and begin registering data.

Buy TEMPer Thermal Sensor

Supported Devices

Support was originally provided by urwen. In NEMS Linux 1.6, support was initially moved to the more up-to-date repository from ccwienk (adds several of the newer TEMPer devices) but then forked to NEMSLinux to add support for TEMPerGold_V3.3 firmware (and others in the future).

NEMS Linux includes support for TEMPer temperature and humidity sensor data. This table also shows which have internal or external sensors. NEMS Linux will always opt for external sensor data, if present.

List of Supported TEMPer Devices
Product	ID	Firmware	Temp	Hum	Int	Ext
TEMPer	0c45:7401	TEMPerF1.4	✔	✘	✔	✘
TEMPer	413d:2107	TEMPerGold_V3.1	✔	✘	✔	✘
TEMPer	1a86:e025	TEMPerGold_V3.3	✔	✘	✔	✘
TEMPer	1a86:e025	TEMPerGold_V3.4	✔	✘	✔	✘
TEMPerHUM	413d:2107	TEMPerX_V3.1	✔	✔	✔	✘
TEMPerHUM	1a86:e025	TEMPerHUM_3.9	✔	✔	✔	✘
TEMPer2	413d:2107	TEMPerX_V3.3	✔	✘	✔	✔
TEMPer2	413d:2107	TEMPer2_V3.7	✔	✘	✔	✔
TEMPer2	1a86:e025	TEMPer2_V3.9	✔	✘	✔	✔
TEMPer2	1a86:e025	TEMPer2_M12_V1.3	✔	✘	✔	✔
TEMPer1F	413d:2107	TEMPerX_V3.3	✔	✘	✘	✔
TEMPerX232	1a86:5523	TEMPerX232_V2.0	✔	✔	✔	✔
TEMPer1V1.1	0c45:7401	TEMPer1F1.1Per1F	✔	✔	✘	✔

Temp: Device contains thermal sensor. Hum: Device contains humidity sensor. Int: Device uses an internal sensor built into the device. Ext: Device supports use of an external sensor probe.

Terminal Output

To receive the JSON output, type: nems-info temper

Sample output from a TEMPer2 with an external sensor attached:

{"0":{"vendorid":16701,"productid":8455,"devices":["hidraw0","hidraw1"],"firmware":"TEMPerX_V3.3","internal temperature":30.12,"external temperature":21.68},"sensors":{"thermal":1,"temp_location":"external","humidity":0,"hum_location":"not_present"},"output":{"temperature":21.68,"humidity":0}}

To receive the JSON output, type nems-info temper

TEMPer devices seem to have an issue on low-powered systems (such as Raspberry Pi) where due to the low power to the USB port, temper.py will respond with errors such as:

Cannot read firmware identifier from device
Unknown firmware ld_V3.1 TEMPerGold_V3.1: b’80800f874e200000’

To remedy this, nems-info silently loops through the output multiple times until a good thermal reading is obtained. The errors are hidden and only the clean JSON output is generated. This all happens very quickly and transparently, resulting in good output every time, with no errors.

Adding to your NEMS NConf

TEMPer check commands are already pre-configured in the NEMS Linux 1.5.2+ demo data. If you have removed them, or are using an older version of NEMS Linux, you can add the checks yourself.

check_temper_temp (temperature check) and check_temper_hum (humidity check) allow you to add TEMPer devices to your NEMS Server. The check has 4 thresholds: Critical Low, Warning Low, Warning High, Critical High. The number you enter may be in either degrees Celsius or Fahrenheit in the case of check_temper_temp. The system will automatically detect which you are using. The OK temperature will be any temperature that falls between Warning Low and Warning High. This way, you can receive alerts from your NEMS Server should the room temperature be either too cold or too hot. For check_temper_hum, the thresholds are in percent (just enter the number, not the percent sign).

Humidity Sensor Support

Sample command line for humidity sensor:

/usr/lib/nagios/plugins/check_temper 20 35 65 80 hum

Check Commands

As of NEMS Linux 1.5.2, both the temperature and humidity sensors are supported, and check commands are included in NEMS NConf.

check_temper_temp
check_temper_hum

Output

Temperature and relative humidity data are checked against both low and high thresholds. If the temperature or relative humidity are either too low or too high, the state of the check command will be affected. The checks are only in an OK state when the current sensor reading is neither too low, nor too high.

NEMS Linux includes perfdata output: Temperature[low], Temperature[high], Humidity[low], Humidity[high] depending which check is performed. Since perfdata aggregation tools do not generally employ a direct means of understanding that a low threshold exists in addition to a high threshold, please be mindful that extra care may be required when designing your perfdata assimilation. E.g., a low warning temperature of 15°C will show critical if the room temperature is 20°C since perfdata does not usually work in the negative direction. NEMS Linux itself is not impacted by this as the state of the check command is correctly reported, however third-party tools which aggregate the perfdata will need extra care.

Calibration

As of NEMS Linux 1.6, both the thermal sensor and humidity sensor can be calibrated within NEMS SST to ensure the highest level of accuracy.

External vs. Internal Sensors

If your TEMPer device supports an external sensor, this will be used if connected. If the external sensor is disconnected, the internal sensor will be selected automatically.