Videotec DTRX3 - Manual (Page 42)

Page 12 MNVCDTRX301_0850
Keyboard phone cable RJ-Jack DTRX3
RS485A connectors white ------------------------ RX-485A
RS485B RJ11 ‘A’ or ‘B’ yellow ------------------------ RX-485B
Note: Terminals RX-485A and RX-485B which have the load inserted, should be connected to terminals TX-
485A and TX-485B respectively of the preceding unit, which also have the load inserted:
NB: For the connection in question (point-to-point) faulty operation of one of the receivers will switch off all the
devices in cascade.
6.9.2 More than one receiver per line, connection with twisted pair cable (multipoint
connection)
All receivers connected to the same line should use the same communication protocol RS485.
For each of the lines the following remarks are valid:
• only one of the keyboards (that at one end of the line) has the load inserted
• only one of the receivers (at the other end of the line) has the load inserted
• the total length of the line should not exceed 1200 m
Line A on keyboard DCS3 has been used for communication with the telemetry. The ends (Keyboard - Receiver
A3) should have the termination resistor inserted. Receivers A1, A2 should not have the termination resistor
inserted. The maximum line length, from end to end (from the keyboard to receiver A3), is 1200 metres.
NB: For the connection in question (multi-point) faulty operation of one of the receivers will not influence the
other receivers.