Elro HE Contact

Feature	Support
Sending
Receiving
Config

Supported Brands

Brand	Protocol
Elro 800 Series	elro_800_contact

Sender Arguments

None

Config

{
  "devices": {
    "contact": {
      "protocol": [ "elro_800_contact" ],
      "id": [{
        "systemcode": 31,
        "unitcode": 0
      }],
      "state": "closed"
     }
  }
}

Option	Value
id	0 - 31
code	0 - 31
state	opened / closed

Optional Settings

None

Protocol

This protocol sends 148 pulses like this

320 960 320 960 320 960 320 960 320 960 320 960 320 960 320 960 320 960 320 960 320 960 320 960 320 960 960 320 320 960 960 320 320 960 960 320 320 960 960 320 320 960 320 960 320 960 960 320 320 9920

It has no header and the last 2 pulses are the footer. These are meant to identify the pulses as genuine, and the protocol also has some bit checks to filter false positives. We don’t use them for further processing. The next step is to transform this output into 12 groups of 4 pulses (and thereby dropping the footer pulses).

320 960 320 960
320 960 320 960
320 960 320 960
320 960 320 960
320 960 320 960
320 960 320 960
320 960 960 320
320 960 960 320
320 960 960 320
320 960 960 320
320 960 320 960
320 960 960 320
320 9920

If we now look at carefully at these groups you can distinguish two types of groups:

1. 320 960 320 960
2. 320 960 960 320

So the first group is defined by a high 4th pulse and the second group has a low 4th pulse. In this case we say a high 4th pulse means a 1 and a low 4th pulse means a 0. We then get the following output:

11111 10000 1 0

Each (group) of numbers has a specific meaning:

• SystemCode: 0 till 5
• UnitCode: 6 till 10
• State: 11
• Check: 12 (inverse state)

11111 10000 1 0

• The SystemCode is defined as a binary number
• The UnitCode is defined as a binary number
• The State defines whether a devices needs to be turned On or Off
• The Check defines whether a devices needs to be turned On or Off (but is inverse)

So this code represents:

• SystemCode: 31
• UnitCode: 1
• State: Opened
• Check: Opened (inverse state)

Another example:

• SystemCode: 0
• UnitCode: 4
• State: Closed
• Check: Closed (inverse state)

00000 00100 0 1

Furthermore the protocol filters out false positives by checking if:

• Every 1st bit of the first 12 groups of 4 bits is always LOW (0)
• 2nd bit of the first 12 groups of 4 bits is always HIGH (1)
• 3rd and 4th bit of the first 12 groups of 4 bits are different (NOT EQUAL)
• Bits 49 and 50 are LOW (0) and HIGH (1) respectively (fixed footer)

This makes the protocol more accurate because it will respond less when arctech_old commands are sent.