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sensate 0.2.1

Sensaphone hub and sensor abstraction library

Sensate provides a pythonic interaction layer for Sensaphone hubs and sensors

Currently supporting the WSG30 (Wireless Sensor Gateway) and the Web600 (wired sensor hub) (new in version 0.2).

If you’d like to help develop Sensate for use with other Sensaphone models, the infrastructure of this library has been designed with modularity in mind.

As most open source libraries, changes should be submitted via diff or pull request, and you should formally accept the terms of the packaged license (in this case, the MIT license).

Purpose

The Sensaphone family of equipment communicates over the SNMP protocol, a protocol generally considered to be bothersome for humans to work with.

Even python libraries for SNMP tend to be a pain.

This library allows you to work with “SensorHub” and “SensorCheck” objects in a much more programmatically natural way.

Setup

To start playing with sensate, it’s recommended (though not required) to use a virtual environment:

Next you can run a “build install”, which will pull in all the dependencies it needs. There aren’t many dependencies, so it shouldn’t take long.

python setup.py build install

That’s it!

Test your installation by…

Usage

In most cases, the following code should work for you. Set HOSTNAME to a reachable hostname on your network or over the internet:

from sensate.sensorhub import SensorHub
hub = SensorHub(HOSTNAME)
print hub.checks
print hub.alarms

That’s it.

hub.alarms prints out a map of type of alarm (‘alarmhigh’, ‘alarmlow’, ‘low_battery’, ‘trouble’) to a list of SensorCheck objects for sensors exhibiting this condition.

hub.checks contains a list of SensorCheck objects with as many addressable attributes as the hub will provide. For example:

SensorCheck for Sensor 1 at wsg30.lan.company.net
{ 'lastalarm': '2/27/2014 1:08:57pm',
  'checktime': datetime.datetime(2014, 3, 7, 23, 23, 1, 90909),
  'hostname': 'wsg30.lan.company.net',
  'name': 'CLIA Reagent Freezer',
  'idx': 1,
  'measurement': -19.2,
  'units': 'C',
  'alarmlow': -25.0,
  'alarmhigh': -15.0,
  'alarm_status': 'OK',
  'measurement_type': 'Temp 2.8k C',
  'serial': '123456' }

The idx attribute (int) represents the numerical index of the sensor on the hub.

The serial attribute (string) is the physical sensor device’s unique identifier.

Note: The WSG30 serial numbers come from the wireless sensor’s XBee transmitter, whereas the Web600’s serial numbers are generated from the last 4 characters of the device’s MAC address followed by 1-2 numbers indicating which Zone the sensor belongs to.

alarm_status will be one of ‘OK’, ‘High’, ‘Low’, ‘Low Battery’, or ‘Trouble’ (the latter meaning that the sensor has become completely unresponsive).

You’ll also notice the checktime attribute, which will be set by sensate at datetime.utcnow().

Both SensorCheck and SensorHub objects have to_dict and to_json methods.

As of version 0.1.2, the JSON conversion uses pyRFC3399 to generate strings for JSON and convert them back into Python datetime objects again.

Tips and Tricks

You may not want to connect to the hub immediately upon establishing the SensorHub object. That’s fine – just supply auto=False as a keyword argument to SensorHub.

Then when you want to perform the checks, use the SensorHub.reload() method.

You can get even more granular about your data retrieval: reload() is just a convenience interface to the following two methods:

SensorHub.discover()
SensorHub.check()

The first method (discover) populates a dictionary called sensors_by_idx which you can access as an attribute of the SensorHub object. discover performs one poll per possible index point (0 to MAX_SENSORS_PER_HUB) to see if there’s a ‘name’ attribute for this index point. Only indexes with names are added to sensors_by_idx

Also, if you supply match=’foo’ to SensorHub instantiation, only those sensors whose name matches ‘foo’ will be collected. This is useful when trying to ignore Battery and Power level on the hubs, or when collecting logically grouped sensors.

The second method (check) uses the sensors_by_idx dictionary to construct SensorCheck objects, which in turn perform the work of collecting values and statuses.

After SensorHub.check() has been run, there are two dictionaries formed for convenient access to the data:

checks_by_idx checks_by_serial

Both of the above are simply dictionary mappings to the SensorCheck objects, with keys being the index point (idx) or the serial number (serial), respectively.

Future

Planned features for sensate include:

SNMP _set_ capabilities (writing parameters to the Sensaphone hub)

Desireable but reliant on outside contributions:

Support for more Sensaphone equipment.

Support and Maintenance

Sensate is being actively developed and maintained at Invitae by its creator, Naomi Most (@nthmost).

You are welcome to file issues on the bitbucket issue tracker.

Pull requests will be reviewed by the package maintainer and approved on a case-by-case basis. Submissions entail acceptance of the MIT License on the part of the submitter.

Questions? Comments? Swear words? Email naomi.most@invitae.com

 
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