Appendix A: Data Interface Information; General - Paradise Datacom P300 Series Installation & Operating Handbook

APPENDIX A: DATA INTERFACE INFORMATION

GENERAL

Unlike previous Paradise Datacom products, the standard interface of the P300 Series Modem DOES
NOT SIMPLY UNPLUG. Instead to reduce the cost of the modem the interface is built as a standard
part of the main PCB and includes RS422, V.35, and RS232 modes. An additional G.703 interface may
be fitted internally to provide front panel selection between RS422, V.35, RS232 and G.703.
IT IS POSSIBLE TO FIT OTHER INTERFACES, and in fact the whole Paradise P14xx range can be
utilised in the P300 series modem. However, prior to fitting another interface the case must be opened,
the standard interface `snapped off` from the main PCB, and a 48 pin connector fitted to the main PCB
to accept the plug in cards. It is advisable to return the equipment to the factory for this to be done,
although it is perfectly possible in the field.
1:1 OPERATION
The standard RS422, V.35, and RS232 interface does not require any resistor packs to be unplugged
for 1:1 redundancy operation. HOWEVER the G.703 option has a switch to set the mode (Normal or 1:1)
and the E1 G.703 card a second switch to select 120 /75 operation. The Normal/1:1 switch on the
G.703 option doubles the impedance (so you can connect the two in parallel) and also selects what
happens when power is removed. If the power is lost in Normal mode the G.703 input and output are
joined so that if in Drop/Insert operation the G.703 signal is looped through multiple equipments, the
other traffic is not affected by a break in the G.703 line. If the power is lost in 1:1 mode the G.703
output goes high impedance if power is lost, allowing its 1:1 partner to carry the traffic.
Unlike previous interfaces, the standard P300 Series interface does not provide a pin on the connector,
which can make the interface go high impedance.
HANDSHAKE LINES
Many interfaces provide optional control lines (such as RTS/CTS etc). It is generally better to implement
these between equipments if possible.
P300H P300 Series Modem Installation and Operating Handbook Page 170