Try setting the communication's in [PABX3 -> COMMUNICATION]:
Siemens 300:
Baud = 9600
Length = 7
Parity = Even
Stop = 1
Baud = 19200
Length = 8
Parity = None
Stop = 1
Baud = 7100
Baud = 4800
Length = 7
Parity = None
Stop = 1
ALSO SEE: Pinlayouts for Siemens Hicom 300
Confirmed: Working at a TOPAZ user.
Siemens Hicom 300 E:
Baud = 9600
Length = 7
Parity = Even
Stop = 1
Confirmed: Working at a TOPAZ user.
Please note:
If the cable configuration is incorrect you will not receive data,
or the data will be scrabled or garbage.