Omvandlare RS-232 – RS-422/485
Converter RS-232 – RS-422/485
RS-232 – RS-422/485 Wandler
INSTALLATIONSANVISNING
INSTALLATION MANUAL
INSTALLATIONS ANLEITUNG
6152-2002
www.westermo.se
MD-42 AC
MD-42 DC
©
Westermo Teleindustri AB • 1999 • Rev. B
Galvanic
Isolation
Transient
Protection
Balanced
TransmissionCEApproved
8 6152-2002
Specifications
Transmission Asynchronous, full/half duplex or simplex
Interface 1 EIA RS-232-C/CCITT V.24,
9-position D-sub female / Screw-terminal
Interface 2 EIA RS-422/RS-485/CCITT V.11
Data rate Up to 115.2 kbit/s
Indicators Power, TD, RD, RTS, CTS, DCD
Insulation Galvanic insulation with opto-coupler (data transmission)
and transformer (supply)
Insulation voltage 1500V
Overvoltage protection Mains: Breakdown voltage 430V at 230V AC
and 230V at 115V AC*
Interface 2: Breakdown voltage transmitter
and receiver 7V
Surge capacity 0.6 kW for 1ms
Power supply 115V*/230VAC +15/–10% 48–62Hz
Fuse 100 mA fast 5x20 mm
Power consumption Max 4VA at 115V*/230V AC
Temperature range 5-50°C, ambient temperature
Humidity 0–95% RH, non-condensing
Dimensions 55x100x128 mm (BxHxD)
Weight AC 0.5 kg, DC 0.3 kg
Mounting At DIN-rail 35 mm
* MD-42 115V AC only
1
23456789
S3:1-6 S2:1-6
123 4 5
MD-42 DC
V24/RS-232-C
RS-422/RS-485/V11
CONVERTER
LINE CONNECTION
-
+
TD
RD
RTSCTS
DCD DT
DS SG
103 104 105 106 109 108 107 102
12-36V DC
POWER
R+ R- T+ T-
PW
V24/RS-232-C
CONNECTION
Warning!
Do not open connected unit
96052-2001
Switch settings
The MD-42 can through different switch settings be adapted to a vareity of running
conditions. To set switches, open the plastic case by removing the top cover.
S2 Selection of signal activating the transmitter
Selection of signal controlling DCD
Selection of CTS delay
S3 Selection of termination with fail-safe 1)
Selection of 2- or 4-wire communication
Transmitter
Factory settings
Transmitter
Activated
by
RTS RTS RTS
RTS Always high
DTR DTR
DTR Always high
RTS
DTR
DTR
CTS
contolled
by
DCD
contolled
by
S2
S2
S2
S2
S3
ON
123456
ON
123456
ON
123456
Termination (4-wire)
Termination (2-wire)
No termination
S3
S3
S3
ON
123456
ON
123456
ON
123456
Termination
with fail-safe
1)
ON
123456
Always high Always lowAlways active
S2
ON
123456
Always high Always highAlways active
S2
ON
123456
ON
123456
CTS-delay
0ms
S2
S2
20ms
S2
ON
123456
ON
123456
Selection of 2- or 4-wire
4-wire
S3
2-wire
S3
ON
123456
ON
123456
ON
123456
1) The fail-safe function forces the
signal state of the receiver to
OFF when the connected
transmitter is in tri-state
(transmitter inactive).
The receiver located furthest
away shall be terminated.
10 6152-2002
N 115V*/230V
L AC power
PE/Protective Earth
I 3 8 103 TD/Transmitted Data
O 2 7 104 RD/Received Data
I 7 6 105 RTS/Request To Send
O 8 5 106 CTS/Clear To Send
O 6 2 107 DSR/Data Set Ready
– 5 9 & 1 102 SG/Signal Ground
O 1 4 109 DCD/Data Carrier Detect
I 4 3 108/2 DTR/Data Terminal Ready
Description
Connections MD-42
Line connection
(5-Position screw-terminal)
Direction
No.
Description
Receiver 1 A’ (R+)
Receiver 2 B’ (R–)
Transmitter 3 A (T+)
Transmitter 4 B (T–)
5 Shield
Power connection (AC)
(3-position screw-terminal)
Terminal connection (DCE)
(RS-232-C/V.24, 9-position D-sub, female/screw-terminal)
I = Input O = Output on MD-42
* MD-42 115V only
Screw
no.
Power
Supply
Drection
Pin
no.
Screw-
terminal
CCITT V.24
Circuit no.
Line connection
1) If shielded cable is used, connect the shield only at one end to avoid ground currents.
4-wire 2-wire
1
2
3
4
5
3
4
5
A’
B’
A
B
A
B
A’
B’
Receiver
Receiver A/A’
B/B’ B/B’
A/A’
Twisted pairs
Twisted pairs
MD-42 MD-42
Transmitter
Transmitter
RS-422
equipment
RS-485
equipment
Transmitter/
Receiver
Transmitter/
Receiver
Shield 1) Shield 1)
The definations R+/R–,T+/T– can be
various between different manufactures.
116152-2002
Switch settings
According to MD-42 AC
Connections
According to MD-42 AC, except power supply
MD-42 DC
Specifications
Power supply 12–36V DC
Power consumption Max 2.3W
Insulation 500V
Fuse F1 1.6A fast 5x20 mm
All other specifications according to MD-42 AC
1 – Voltage
2 + Voltage
Connection
no.
Power
Supply
Transmission range (interface 2)
Use twisted pair cable. Max transmission range 1200 m.
(cable specifications 0.3 mm
2
and capacitance 42pF/m ).
The transmission range will increase if a cable with lower
capacitance and larger diameter is used.
Use shielded cable in heavy industrial environments.
12 6152-2002
Hints
RS-422/485 was designed for multidrop applications. When a system is installed it should
form a bus structure (see diagrams). Star shaped networks should never be created,
there are other Westermo products designed to work in star net applications.
To correctly install, an RS-422/485 network should be terminated at the correct points.
The recommendation is to terminate the receiver on the master unit and the final bus
slave unit. See diagrams for details of how this is done with RS-485 (2-wire) and RS-422
(4-wire).
On 4-wire systems when the MD-42 is on a slave system, it’s transmitter is linked to
the same bus as all the other slave transmitters. A status signal RTS or DTR is used to
control the MD-42’s transmitter, to ensure only one slave is active on the bus at one
time. The status signal is also used to control direction for RS-485 (2 wire) transmission.
If any problems do occur on set up of the MD-42, the LED’s will be helpful.
• PWR: The unit has power.
• RD: Data received on the RS-422/485 interface.
• DCD: Simulated carrier due to the setting of S2.
• CTS: Follows RTS.
• RTS: Indicates that the RS-422/485 transmitter is activated.
• TD: Data received on the RS-232/V.24 interface.
136152-2002
Max 1200 metre and 32 connections
Max 0.3 metre
Max 0.3 metre
3 (A/A’)
4 (B/B’
B/B’A/A’
B’
A’
BAB’A’BA
B’
A’
BA
B/B’A/A’
B/B’A/A’
1 (A’)
2 (B’)
3 (A)
4 (B)
Termination
Termination
N.B. R+/R–, T+/T– definitations are not standard, it can help to shift A and B
if the unit does not work.
6152-2002 12.99 TunaTryck AB, Eskilstuna, Sweden
Westermo Teleindustri AB • S-640 40 Stora Sundby, Sweden
Phone +46 16 612 00 Fax +46 16 611 80
E-mail: info@westermo.se • Westermo Web site: www.westermo.se
Westermo Teleindustri AB have distributors in several countries,
contact us for further information.
Block diagram
Westermo Data Communications GmbH
Bruchsaler Straße 18, 68753 Waghäusel
Tel.: +49(0)7254-95400-0 • Fax.:+49(0)7254-95400-9
E-Mail: westermo.germany@t-online.de
Westermo Data Communications Ltd
Solent Business Centre • Millbrook Road West
Millbrook, Southampton • SO15 0HW
Phone: +44(0)2380 704 611 • Fax.:+44(0)2380 702 682
E-Mail: sales@westermo.co.uk
Subsidiaries
SG
Power supply
A'
B'
A
B
Shield
V.11/RS-422
RS-485V.24/RS-232
TD
RTS
DTR
DCD
CTS
RD
DSR
D-sub housing
2)
5
0V
PE
1
2
3
4
PWR
TD
+5V
DCD
+5V
3
7
4
1
1
2
3
4
5
RTS
20mS
CTS
RD
8
2
+5V
S3
+5VB
6
1K
100R
1K
S2
6
0VB
5
F1
R44R
PE
R45
PE
0VB
0VB
+5VB
0VB
+12V
S2
6
4
S3
3
5
S3
Volt
sel
115/
230V
1
2
-12V
0V
+5V
2)
Insulated power supply
2)
1)
1) 0 ½ resistor R45 is normally not mounted.
2) Metal housing on D-sub is connected to PE if R is mounted. R = R3 on DC-model
(normally mounted), R = R1 on AC-mod (normally not mounted).
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