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8DBRA – How To Serve 3 Local Ports From One Incoming DS-0
September, 2012
The following illustrates how to have RS232 data on a single incoming DS0 at a remote AM3440
8DBRA card be duplicated on 3 of the RS232 ports at the same time. This application is typically
used for SCADA where multiple devices are polled from the same host port and the data arrives for
all three devices over a single DS0.
This application uses the 1+1 Port Backup function of the 8DBRA card. Local SCADA devices can
use ports 3, 5 and 7. A crossover jumper cable is used between RS232 Port 1 and RS232 Port 2.
The RS232 Port 2 is mapped to Virtual Port 1, Time Slot 2, RS232 Port 3 is mapped to Virtual Port 1,
Time Slot 3. In the cross connect map of the AM3440, Virtual Port 1, Time Slot 2 is mapped to Virtual
Port 1, Time Slot 3.
Below is the setup for the host end RS232 port. Note that it is set for 64 Kbps synchronous operation
and the asynchronous data transitions are oversampled.
SLOT 2 X50 PORT 1
=== Setup Configuration ===
23:20:25
09/19/2012
ARROW KEYS: Cursor move; Change options by TAB, or by typing
[-------X50 MUX
SYNC mode
Rate
Phase
4.8k sel
Clock
Data
RTS
TTM
DCD
Interface
LOCAL --------]
: NO_MUX
: SYNC
: 64K
: fixed
: fixed
: Normal
: Normal
: Permanent
: Off
: Permanent ON
: 8RJ
Page 1
The 8DBRA card at the remote location is set to 1+1 Backup
SLOT 6 8DBRA P1
=== Backup Setup ===
23:23:12
09/19/2012
ARROW KEYS: Cursor move; Change options by TAB, or by typing
Backup Type : 1+1 Port Backup
Warning!! Change Backup Type will clear map.
Below is the mapping of the physical RS232 ports of the 8DBRA card to the Virtual Ports of the
8DBRA card. RS232 Port 1 is mapped to Virtual Port 1, Time Slot 1. The VP1, TS1 is cross connected
to the incoming T1 DS0 that is carrying the polling data from the host computer.
RS232 ports 2 and 3 are mappeds to VP1, TS2 and VP1, TS3 respectively. VP1, TS2 and VP1, TS3 are
mapped to each other. See the Map34 mapping information that follows.
SLOT 6 8DBRA P1
=== Port Map Setup ===
23:30:30
09/19/2012
ARROW KEYS: Cursor move; Change options by TAB, or by typing
[Setup]
Virtual Port:
TS start
:
Total TS
:
RS232 Port :
Command
:
P1
01
01
1
Set
[Display]
Port TS: 1
VP1 MAP: 123iiiii
VP2 MAP: iiiiiiii
VP3 MAP: iiiiiiii
VP4 MAP: iiiiiiii
9
17
25
32
iiiiiiii iiiiiiii iiiiiiii
iiiiiiii iiiiiiii iiiiiiii
iiiiiiii iiiiiiii iiiiiiii
iiiiiiii iiiiiiii iiiiiiii
Note: i=idle, 1~8=RS232 port number
Page 2
The mapping below illustrates the host end RS232 port being mapped to a T1 for transmission to the
remote AM3440 location.
Page 3
The screen below shows the incoming DS0 on the T1 being mapped to the 8DBRA VP1, TS1 which is
mapped on the 8DBRA card to RS232 Port1.
Page 4
The screen below shows VP1, TS2 mapped to VP1, TS3. This mapping takes the data coming in on
RS232 Port 2 and maps it to RS232 Port 3.
RS232 Port 1 has a crossover cable to RS232 Port 2. Connect the signal grounds 1 to 1 or 7 to 7.
Crossover the transmit and receive data leads 3 to 5 and 5 to 3.
1 to 1
or
7 to 7
and
3 to 5
and
5 to 3
Polling data comes out RS232 Port 3 because Port 2 is mapped to Port 3. Polling data comes out
Port 5 because of the 1+1 Backup setting of the 8DBRA card, with Ports 1 and 5 paired. Polling data
comes out Port 7 because the 1+1 Backup setting of the 8DBRA card pairs ports 3 and 7. No polling
data comes out RS232 Port 6 because the data into RS232 Port 2 is from the wrong direction, the
physical port side rather then from the Virtual Port side.
Page 5
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