Polycom C16 - Manual (Page 356)

Design Guide for the Polycom SoundStructure C16, C12, C8, and SR12
A - 14
The argument defines the physical channel type of the physical
channels in the virtual channel. The argument is a system defined
text argument that must be one of the following.
stereo A stereo virtual channel
control A control channel such as logic input or
output or IR receiver
control_array A collection of control pins, in other words
a group of logic input or output pins
Virtual channel type Description
Physical channel type Description
cr_mic_in The physical channel is one of the mic/line
inputs on a conferencing device (for
example, the physical channel supports
echo cancellation).
cr_line_out The physical channel is one of the line
outputs on a conferencing device.
sr_mic_in The physical channel is one of the mic/line
inputs on a sound-reinforcement device
(for example, the physical channel does
not support echo cancellation).
sr_line_out The physical channel is one of the line
outputs on a sound reinforcement device.
pstn_in The physical channel for the receive
signal from the analog telephony
interface.
pstn_out The physical channel for the transmit
signal to the analog telephony interface
sig_gen The physical channel is the signal
generator input.
submix The physical channel is one of the
sub-mix channels.
clink_in The physical channel is one of the
ConferenceLink inputs.
clink_out The physical channel is one of the
ConferenceLink outputs.
digital_gpio_in The physical channel for the digital logic
input pins