[Elecraft] PTCiiUSB Modem ACC instructions to KX3/KX2 TTL or V24?

[Chris]

My KX2 operates Pactor 2 with RMS Express and Airmail on my PTCiiUSB
modem with the KX2 ACC cable for changing frequency.  But I also want to
connect the PTCiiUSB rig controls directly to the KX2 ACC socket to
avoid having to use the extra ACC cable.  I know the PTCiiUSB allows the
Kenwood instruction set that works on the KX3 and I think it also has
the K3 instruction set.  The connections are clear and making the cable
will be easy, except that the PTCiiUSB offers the options of TTL or V24
for the RXD and TXD connections.  Does anyone know whether the KX2 and
the KX3 use the TTL or the V24 protocols and whether connecting to the
wrong protocol will cause damage?

Chris, G4BTN