MDUI - 4222 - Connection Details - IG002R02.pdf

General
The MDUI is a four port (3 RS-232 and 1 RS-422A) communications interface configured as 1 in and 3 out.
Any one of the ports can be configured as the upstream port (primary), the remaining three ports are then downstream
(secondary). An Aux RS-232 port is provided to enable diagnostic information to be accessed.
RS-422A connections can be configured as single pair RS-485 connections by changing the jumper settings.
The main uses of the MDUI include:
1. Conversion between different comms protocols.
2. To split individual RS-232 lines where multiple leased line modems are required for connection to remote sites.
3. Galvanic isolation of segments of the JANUS comms line where there are differences in ground potential.
4. To supervise and control two PCs in order to maintain a ‘Back-up’ system for live JANUS Comms. A MDUI
complete with supervisory software running on Windows NT will change over the JANUS Comms connections to a
back-up PC should the main PC fail.
Drive
TX
RX
Fault
Drive
TX
RX
Fault
Drive
TX
RX
Fault
Drive
TX
RX
Fault
Pulse
Status LEDs
Port 1
Port 2
Port 3
Port 4
P = F =
1
2
3
4
Aux I/O
Connector
1
8
OFF
AUX 4
Transmit/Receive
pin reverse jumpers
ON
Configuration Switches
Diagnostic Port Comms Parameters
Baud rate
Data bits
Stop bits
Parity
19200
8
1
None
(See note 5)
Error Message Format
CAS - Collision, data received simultaneously on more than one port
SBM - Stop bit missing
FSS - False start, very short duration noise pulse received.
No port number will be given
DCH - Data changed within one bit time window
TOR - Transaction overrun, too many characters in transaction
ICD - Illegal character detected
RS-422A or RS-485
selection jumpers
Handshake
jumpers
(See note 6)
Transmit/Receive
pin reverse jumpers
Line termination and
screen connection
jumpers
RS-232 to RS-422A Converter
MDUI-4222
TX-A
TX-B
RX-A
RX-B
SCRN
(Port 3)
2
1
Power Supply
3
2
1
- VE
+ VE
SCRN
RX-B
RX-A
TX-B
TX-A
SCRN
(8)
(3)
(2)
(7)
SCRN
(8)
(3)
First IDC/IPC
Upstream comms
TX-A
TX-B
RX-A
RX-B
SCRN
TX-A
TX-B
RX-A
RX-B
SCRN
Downstream
Comms
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(2)
(7)
OFF
ON
1
Power Supply
+12V
GND
(See note 3)
PWR 4
Line Termination
(RS-422/485 Ports)
SCRN
RX-B
RX-A
TX-B
TX-A
SCRN
RX-B
RX-A
TX-B
TX-A
RS-422A or RS-485
Selection
RS-485
RS-422A
RS-485
RS-422A
Jumper Settings
RS-422A selected
RS-485 selected
Sw1 Switch Settings
8
Unused
Unused
Unused
Pulse LED (See note 4)
1200 Baud
2400 Baud
4800 Baud
9600 Baud
Port 1
Port 2
Port 3
Port 4
Screen Connection
(RS-422/485 Ports)
SCRN
RX-B
RX-A
TX-B
TX-A
SCRN
RX-B
RX-A
TX-B
TX-A
Screen
connected
Screen
broken
Transmit/Receive
pin reverse
(RS-232 & diagnostic ports)
Standard
configuration
TX/RX pins
reversed
Primary port
selection
Power
from
IDC PSU
Battery
Notes
1. Status LEDs
The transmit and receive of the primary and
secondary ports will always be reversed.
The red Fault LED indicates the respective port
has been disabled. This occurs when error rate
threshold is exceeded. All four Fault LEDs
flashing indicates power supply low voltage.
2. Connections
All RS-232 ports have the same configuration.
A comms segment (maximum length of 1200M)
remains part of the original comms line.
Ports 1 & 2 can be connected using either the ‘D’
type sockets or screen terminals.
Screen connections on non-isolated ports (3 & 4)
can be broken to remove earth loops.
3. Power Supply
A 1 Amp power supply is suitable for one or two
MDUI boards, which can be fitted in a standard
wall mounting enclosure. Connect the 0V power
supply rail (Output - ) to chassis earth to provide
a reference point.
4. SW1/4
Must be set to ON or the board will not run.
5. Aux I/O Port
Used for polling fail alarm.
6. Handshake Jumpers
These should not be set .
IG002R02
Multi-Drop Universal
Interface 4222
MDUI-4222
Connection Details
Grosvenor Technology Ltd, Millars Three,
Southmill Road, Bishop’s Stortford,
Hertfordshire. Tel: +44 (0)1279 838000
grosvenortechnology.com

Typical Applications
Leased Line Link
Previous IDC/IPC
Downstream comms
TX-A
TX-B
RX-A
RX-B
SCRN
TX-A
TX-B
RX-A
RX-B
SCRN
MDUI-4222
(Port 3)
TX-A
TX-B
RX-A
RX-B
SCRN
Next MDUI-4222
(Port 4)
Auto Changeover Configuration
Network
Server A
Server B
Com Port
Com Port
Server B
MDUI-4222
(Port 3)
TX-A
TX-B
RX-A
RX-B
SCRN
(Port 2)
First IDC/IPC
Upstream Comms
TX-A
TX-B
RX-A
RX-B
SCRN
TX-A
TX-B
RX-A
RX-B
SCRN
Modem
Modem
RS-232 Cables
9 way D-type Male-Female
pin to pin
Leased Line
Next IDC/IPC
Upstream Comms
(Port 1)
Port 4 Port 3
Port 2
MDUI-4222
(Port 2)
RS-422A
RS-232
From downstream port
of previous IDC/IPC
Modem
TX-A
TX-B
RX-A
RX-B
SCRN
MDUI-4222
(Port 3)
TX-A
TX-B
RX-A
RX-B
SCRN
TX-A
TX-B
RX-A
RX-B
SCRN
Port 4
Port 3
Port 2
RS-422A
Server A
To upstream port
of first IDC/IPC
Leased Line
MDUI-4222
Port 1
Modem
RS-232
MDUI-4222
Port 1
To next MDUI
RS-232 Fibre Link
Previous IDC/IPC
Downstream comms
Port 4 Port 3
Port 2
Port 1
MDUI-4222
RS-422A
RS-232
TX-A
TX-B
RX-A
RX-B
SCRN
From downstream port
of previous IDC/IPC
DVR-232/1 or 2xST
Fibre Link
TX-A
TX-B
RX-A
RX-B
SCRN
RS-232
To next MDUI
MDUI-4222
(Port 3)
TX-A
TX-B
RX-A
RX-B
SCRN
7
2
3
8
SCRN
MDUI-4222
(Port 2)
3
2
7
Male
TX
RX
SCRN
DVR-232
Fibre
Link
SCRN 7
RX
TX
Male
DVR-232
2
3
Next MDUI-4222
(Port 4)
2
3
5
TX-A
TX-B
RX-A
RX-B
SCRN
MDUI-4222
(Port 3)
Next IDC/IPC
Upstream Comms
TX-A
TX-B
RX-A
RX-B
SCRN
TX-A
TX-B
RX-A
RX-B
SCRN
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