IR emitters are used by CommandIR to transmit the remote-control commands to your A/V devices, driven by CommandIR's hardware-generated signals. For each device:
There are two ways to select IR emitters using LIRC software:
irsend set_transmitters method
This method is somewhat depreciated as it cannot guarantee the correct emitter(s) are chosen if commands become backlogged. However, it is the only way to select more than 1 emitter at once.
The set_transmitters directive of irsend will set which emitters the following irsend commands will be transmitted on. Examples:
irsend set_transmitters 1 (select emitter #1)
irsend send_once deviceName buttonName (transmits on emitter #1)
irsend set_transmitters 2 3 (select emitters #2 and #3)
irsend send_once deviceName buttonName (transmits on emitters #2 and #3)
irsend set_transmitters 5 6 (select emitters #1 and #2 on 2nd CommandIR in multi-device system)
irsend send_once deviceName buttonName (transmits on emitters #1 and #2 on 2nd CommandIR)
irsend set_transmitters 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 (selects all emitters on 4 CommandIRs)
irsend send_once deviceName buttonName (transmits on all emitters)
irsend settransmitters-X method
Install CommandIR's own lircd.conf into your own lircd.conf to access many CommandIR-specific commands, including settransmitters-X. This will allow you to select which emitter the next commands should be transmitted on, and will never transmit a command to the wrong device regardless of backlog or busyness. Examples:
irsend send_once commandir settransmitters-1 (selects emitter #1)
irsend send_once hauppauge ok (sends command on emitter #1)
irsend send_once commandir settransmitters-6 (selects emitter #2 on 2nd CommandIR in multi-device system)
irsend send_once hauppauge ok (sends command on emitter #2 on 2nd CommandIR).
Download CommandIR's lircd.conf from here.
Identify the location of the remote-control receiver on your A/V device - It's usually inside behind a dark plastic window but can usually be seen by holding up your device to a light. If you cannot see it (and it is not labeled), then hold your remote up close to the device moving from one side to the other while pressing buttons to see where they are best detected. 