Milestone LD-15U User Manual

RS232C < - > RS485 CONVERTER’S MANUAL

Model: LD15U

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

INTRODUCTION
Milestone’s model LD-15U is a RS232 to RS 485 converter is designed for high­speed data transmission between computer system and or peripherals over long
distance under high noise conditions. They provides dual line interface per signal.

APPLICATIONS
Application for these converters can be for factory automation, programmable logic
controllers, attendance recording systems, Barcode Readers, remote data
transmission, remote terminals, EPABX etc.

Technical Specifications

Input (RS232C)

Output (RS485)

Signal Protection

Selection Switch – 1

Selection Switch – 2

Maximum Distance

Output Cable

Transient Protection

Indication

Power Supply

Size

RS232C - TxD, RxD, DSR (for control), GND

RS485 – Tx+, Tx-, Rx+, Rx-

Each signal is protected by spike suppressor,

Opto-Isolation

Fuse protection

Rear side has 2 way Select switch for
Selecting 2 wire or 4 wire mode in RS422 / RS485.

1. Rear side has 3 way Select switch for selecting AUTO
Mode (no Handshaking Signal),

2. DSR+ Mode (+12V Control) for controlling data flow

3. DSR– Mode ( -12V Control) for controlling data flow

1.2 Kms. @ 19,200 bps

Shielded twisted pair cable –90 Ohms/km. (Not supplied)

2500 V Peak

Power LED Rx LED Tx LED DSR

230 V, 50 Hz

117 mm x 105 mm x 55mm

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

INSTALLATION INSTRUCTIONS

 Switch Settings

1. 2-WAY SELECT SWITCH:
Select 2-wire (half duplex) or 4-wire (full duplex) mode on 2-way switch on the

back panel.

2. 3-WAY CONTROL SWITCH: (Optional / Old Models) (In new models, it is fully automatic. No selection required)
A. Position 1 - Auto - No Handshake Control
B. Position 2 - DSR + (+12V) to enables RS485 output
C. Position 3 - DSR - (–12V) to enables RS485 output

TABLE I: RS 232 Port – D9 Female Connector

Pin No.

Signal Name Input / Output

2

3

4

5

6,8

Tx Output

Rx Input

DSR Input

Signal Ground -

DTR, DTS Output

TABLE II: Output port-D9 Male connector

Pin No.

3 -Rx

4 +Rx

5 +Tx +Tx/+Rx

6 -Tx -Tx/-Rx

7 GND. GND.

1 Frame Ground Frame Ground

Signal Name Input / Output

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

LED Indication:

A Power Power to the unit

B TD TX Data on RS485

C RD RX Data on RS485

D DSR Transmit Control

TABLE III: RS 232 Cable

Computer End RS232 Port on LD-15U

Pin No on (D-25) Pin No on (D-9) Signal Pin No (D-9, F)

Signal

2 3 Tx 2 Tx

3 2 Rx 3 Rx

6 6 DSR 6 DTR

7 5 GND 5 Sig. Gnd

20 4 DTR 4 DSR

4,5 7,8

RTS.CTS

8 RTS

The above connections are for Standard PC COM Port. Please verify these

connections for any other system or terminal before making the cable.

LONG DISTANCE CABLE LAYING

Long distance cable between two RS422/RS485 interfaces must be a twisted pair

shielded cable. The pair should be used for each signal type + and – signal. This

gives high common mode noise rejection. While laying the cable, care should be

taken not to lay this cable parallel to power line cables. The cable resistance should

not be more than 90 ohms/1000 meters. The cable should be run through conduit

pipe for physical protection.

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

Cable Diagram for RS-422 / 485:

TABLE IV: OUTPUT CABLE – 4 Wire (RS-422)

D9-Male (LD-15U)

-Rx 3 -TX

+RX 4 +TX

+TX 5 +RX

-TX 6 -RX

TABLE V: OUTPUT CABLE – 2 Wire (RS-485)

Pin No. Instrument

D9-Male (LD-15U)

+TX / + RX 5 +TX / +RX

-TX / - RX 6 -TX / -RX

 Above Cable diagram is for, from unit to (ML LD 15 U) to P.L.C.

 DB-9 Male is on ML LD 15U. So, you need to use DB-9 Female at RS-422 /

485 LD 15U side.

Pin No Instrument

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

Testing Manual for

RS-232 to RS-422/RS-485 Converter

(ML LD-15 U)

For testing RS-232 to RS-485 Converter, one should follow the following
steps:

1. Check the physical condition of the unit.

2. Plug-in the Converter in the power socket to check the power on the

unit.

3. Attach the input cable, which comes with the Converter to get the

input of RS-232 signal from the computer.

4. Prepare the Loop-back dongle and attach it on the output (RS-

422/485) Port. To prepare this dongle, you need to short pin no. “3 & 6”

and “4 & 5” of a 9 pin Female connector at the soldering side. Connect

it on the Output port Do not connect any other pin.

5. Start the Hyper Terminal Software for testing the converter. Go to “Start

-> Programs -> Accessories -> Communications -> Hyper Terminal”.

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

6. Give the proper file name when asked at the start up. (See image 1.01)

(Image 1.01)

7. Provide proper COM Port when asked to. (See image 1.02)

(Image 1.02)

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

8. Set the properties of the COM Port as shown in the image 1.03

(Image 1.03)

9. Go to File Menu + Properties. Go to Setting Tab in the Properties

window. (See image 1.04)

www.interfaceproducts.info

(Image 1.04)

Phone: [phone] / 97 / 98 (M) 0-98253-50221

10. In the Settings Tab Click on “ASCII Setup…”. In the ‘ASCII Sending’ part,

check the box of the line “Echo typed characters locally”. Then Click

OK. Again click OK for Properties window. (See image 1.05)

(Image 1.05)

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221

11. Set the converter to ‘4 wire’ by a slide switch, situated on the rear

panel of the converter. Now, if you type anything it will give display

typed twice. (See image 1.06)

(Image 1.06)

If you can see the terminal window as per image 1.06 successfully, it means

that the converter is working properly.

www.interfaceproducts.info

Phone: [phone] / 97 / 98 (M) 0-98253-50221