XEZ 4008 emulator and gateway to MQTT broker

This python application opens a RS485 serial device and emulates a XEZ 4008 device and subscribes to a MQTT broker for topics amt/{1,48} and publishes it as open or closed to a AMT 4010 alarm central from Intelbras.

XEZ 4008 and AMT 4010

The AMT 4010 is a alarm central from Intelbras which communicates with expansion devices to connect additional PGMs, additional PIR motion sensors, wireless sensors and remote controls.

One of these expansion devices is the XEZ 4008, which connects to 8 wired PIR motion sensors and advertises them in the AMT 4010 alarm central.

The communication is done through, what Intelbras calls, a A-B bus. Which is a RS485 with 4800 8N1 configuration in a protocol that resembles somewhat MODBUS RTU packets.

Getting started

Clone the repository to a Linux machine with a RS485 adapter. Create a virtualenv:

$ virtualenv venv

Install dependencies:

$ source ./venv/bin/activate
$ pip install crcengine
$ pip install pyserial
$ pip install paho-mqtt

And then you can run it:

$ python -m xez-4008 -p 1883 --host mqtt-broker.com --address 1,2,3 -d /dev/ttyUSB0

Make sure you have permission to open your serial device and that it is configured for low_latency with setserial package:

$ sudo setserial /dev/ttyUSB0 low_latency

Low latency

Use of low_latency is required for this program to work correctly, because the MODBUS-like protocol uses timing for synchronization of packet begin and end. Otherwise it may concatenate packets and discard them because CRC doesn't match.

Protocol

Protocol is simple and resembles MODBUS RTU. It starts with a byte address, for example 0x0d for XEZ configured in address 1.

It uses a CRC with the following specifications:

width=8 (1 byte)  poly=0x01  init=0xff  refin=false  refout=false  xorout=0x00  check=0xce  residue=0x00  name=(none)

The CRC is the last byte of every packet and for calculation purposes it must be filled with zero.

Home Assistant

If you want to configure this for HomeAssistant, you must first configure HomeAssistant to use the same MQTT Broker, and you can use a MQTT switch by adding something like the following to configuration.yaml.

switch:
 - platform: mqtt
   name: "Virtual sensor 1"
   command_topic: "amt/25"
   payload_on: "on"
   payload_off: "off"
   qos: 1
   retain: true

There's no support for discovery yet.