Black Box PSD-4, User Manual, Page: 14 / 17

CHAPTER 5: Technical Guide
13
5. Technical Guide
5.1 Control Signals
M
AIN
C
HANNEL
C
ONTROL
S
IGNALS
RTS (DCD)
• In RTS/DCD contention mode: follows RTS (DCD) of the selected sub-channels.
• In Data Contention mode: ON if one of the sub-channels RTS (DCD) is ON.
CTS
On only when the CTS signals of all active sub-channels are ON. A sub-channel is active if it is
connected to a modem and the DSR signal is ON (enables connection of dialup modems to the PSD).
DSR (DTR)
ON if one of the sub-channel’s DTR (DSR) is ON.
S
UB
-C
HANNEL
C
ONTROL
S
IGNALS
RTS (DCD)
• Follows the main channel RTS (DCD) (unless the sub-channel is disabled).
CTS
• In RTS contention mode: selected sub-channel follows DTS signal of main channel.
• In Data Contention mode: sub-channel receives CTS from main channel immediately after it raises
RTS (unless the sub-channel is disabled).
DSR (DTR)
Follows the main channel DSR (DTR).
5.2 Block Diagrams
Figures 6 through 9 illustrate the flow of data and control signals in the PSD, in different DTE/DCE
configurations:
Main Sub-
Figure Channel Channel
Number Configuration Configuration
6 DTE DCE
7 DTE DTE
8 DCE DCE
9 DCE DTE