Hi there,
The pin outs of SpeakerLink on Duncan's Info Site.
Pin 3 is TxD, pin 5 ground, pin 6 RxD


561, HD621, DSP5000s(24/96), DSP33C, DSP33 surrounds, Pioneer DV575A CD/SACD/DVD-A, Panasonic DB170
(561 to be replaced with G68 shortly.)