The protocol used by the X-10 IR543 and IR7243 is illustrated below.
Each code starts with a 4ms burst of carrier followed by a 4ms silence. This start code helps to set the ACG in the receivers which dynamically adapt to signal strength. After the start code, there are 10 bits with bit time of 8ms. A binary 1 is represented by a 4ms pulse followed by a 4ms silence. A binary 0 is represented by 1.2ms pulse followed by a 6.8ms silence. A final 12ms pulse marks the end of the code.
The actual codes are only 5 bits but all are sent a second time in complementary form.
The overall time to send one code is about 100ms. Timings will vary from one transmitter to another but are repeatable for a specific transmitter.
Addresses and function codes can be sent separately.
The actual codes for each address and function are given in the table below.
COMMAND D1 D2 D4 D8 D16
1 0 1 1 0 0
2 1 1 1 0 0
3 0 0 1 0 0
4 1 0 1 0 0
5 0 0 0 1 0
6 1 0 0 1 0
7 0 1 0 1 0
8 1 1 0 1 0
9 0 1 1 1 0
10 1 1 1 1 0
11 0 0 1 1 0
12 1 0 1 1 0
13 0 0 0 0 0
14 1 0 0 0 0
15 0 1 0 0 0
16 1 1 0 0 0
All Units Off 0 0 0 0 1
All Lights On 0 0 0 1 1
On 0 0 1 0 1
Off 0 0 1 1 1
Dim 0 1 0 0 1
Bright 0 1 0 1 1
Note: The IR543AH is a modified IR543. It was developed by Laser Systems and uses a proprietary extension to the X-10 IR protocol. The IR543AH can handle all 16 housecodes and adds Preset Dim and Extended codes to the functions supported.
Both the IR543 and IR543AH receive IR codes, verify that they represent a supported X-10 command, translate the data to the X-10 PLC protocol and transmit the translated command to the powerline. While transmitting to the powerline they cannot receive IR so sequential commands need to be paced to assure the IR543 or IR543AH are again ready to receive IR.
Standard X-10 commands take fixed amounts of time that depend both on the command and on the mains frequency (50Hz or 60Hz). An address command takes 22 powerline cycles. Standard function commands also take 22 powerline cycles. Dim/bright and extended commands can take longer. The IR543 and IR543AH can only send dim/bright in normal 6% steps which also take 22 powerline cycles. This means the IR543 and IR543AH are deaf to IR for the 0.367 seconds (@60Hz) or 0.44 seconds (@50Hz) it takes to transmit a command to the powerline. Added to the 100ms duration of the IR code, this means that IR commands need to be about 1/2 second apart. For the IR543AH, extended codes contain more data bytes and take a bit longer to send.
The IR7243W from X-10 Europe has copied the protocol extensions devised by Laser for the IR543AH.
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