Guide to using SNMP with your Room Alert 3E

SNMP is a great way to integrate your environmental monitoring system into your existing network management system. This guide provides a short tour of all the information you can access via SNMP from your Room Alert 3E.

A Short Introduction to SNMP

The Simple Network Management Protocol is a standard for querying, setting and alerting a wide variety of management information from a device. There are two main system components in SNMP. The first the the SNMP agent. The agent is the entity that responds to queries and optionally send alerts in the form of SNMP traps. The SNMP client requests information from the agent and then logs the data as necessary. A standard network protocol means it doesn't matter what operating system you are running, you can interact with any other compliant SNMP agent from any SNMP client.

If you want a fuller explanation of SNMP, please read Guide to SNMP?

SNMP on the Room Alert 3E

The Room Alert 3E supports SNMP version 1. If you try to use the Room Alert with a higher version, like 2c or version 3 you will likely get a response like Timeout: No response from <Room Alert 3E IP Address>.

The Room Alert 3E has two ways to format the sensor readings. You control the sensor reading format using the admin portal built-in to your Room Alert 3E. Go to the Settings > SNMP section. Enable the Use 2 digit SNMP property to round the sensor reading to two digits or disable to use 4 digit SNMP values. The default is set to 4 digit SNMP values.

Available Information via SNMP

Internal Temperature Sensor

The internal temperature sensor is located inside the case of the Room Alert 3E. The sensor is always present and cannot be switched off.

Description	Full OID	Type	Example Value
Current temperature in Celsius	.1.3.6.1.4.1.20916.1.9.1.1.1.1.0	Integer	2393
Current temperature in Fahrenheit	.1.3.6.1.4.1.20916.1.9.1.1.1.2.0	Integer	7507
Label	.1.3.6.1.4.1.20916.1.9.1.1.1.3.0	OctetString	Internal Sensor

External Digital Sensor

The external digital sensor is connected to the Room Alert 3E using the RJ-11 connector. When the external digital sensor is not connected the Room Alert 3E will not respond when you request the values below.

Description	Full OID	Type	Example Value
Current temperature in Celsius	.1.3.6.1.4.1.20916.1.9.1.1.2.1.0	Integer	2443
Current temperature in Fahrenheit	.1.3.6.1.4.1.20916.1.9.1.1.2.2.0	Integer	7507
Current relative humidity	.1.3.6.1.4.1.20916.1.9.1.1.2.3.0	Integer	5148
Current heat index in Fahrenheit	.1.3.6.1.4.1.20916.1.9.1.1.2.4.0	Integer	7597
Current heat index in Celsius	.1.3.6.1.4.1.20916.1.9.1.1.2.5.0	Integer	2442
Label	.1.3.6.1.4.1.20916.1.9.1.1.2.6.0	OctetString	Ext Sensor 1

External Switch Sensor

The external switch sensor connects to the Room Alert 3E using the two pin connector terminal. Whether a switch sensor is connected or not, the Room Alert will respond to the values outlined below.

Description	Full OID	Type	Example Value
Switch state	.1.3.6.1.4.1.20916.1.9.1.2.1.0	Integer	0
Label	.1.3.6.1.4.1.20916.1.9.1.2.2.0	OctetString	Switch Sen 1

This article was written using a Room Alert 3E with software version 2.0.0. Prior or later revisions of the software may vary. I would urge anybody running version 2.0.0 to upgrade to the latest firmware as at least one bug has been fixed with the MIB files. You may struggle to compile the Room Alert 3E MIB file if you use the Room Alert 3E version 2.0.0 firmware. I used Net-SNMP version 5.7.3 to explore the SNMP data on my Room Alert 3E.