Omega Products LDM485-P User Manual

J-15

⻬ Complete Isolation

with Optical Couplers and Power DC-to-DC Converter

⻬ Industrial Surge

Protection Devices

⻬ Six LED Diagnostic

Indicators

⻬ 19.2K Baud at 3 Miles

(5KM), 57.6K Baud at

0.5 Miles (0.8KM)

⻬ Request-to-Send, Clear-

to-Send Handshake

⻬ Tri-State Outputs for

Multidrop Applications, up to 64 Devices

⻬ Selection of Connectors ⻬ Wide Operating

Temperature Range

⻬ Solderless Screw

Terminal Field Connections

LDM485

Fully Isolated Limited Distance Modem, RS-232/422 Converter

The LDM485 is a compact RS-232 to RS-485 con verter which fea tures a complete electrical iso la tion bar rier and heavy duty elec tri cal surge protectors. These devices feature a rugged alu mi num enclosure small enough to mount on the back panel of typical computer equipment, saving valuable desk and floor space. Isolation is pro vided by optical couplers and a DC-to-DC converter. The RS-232 con nec tion is through male or female EIA 25-pin con nec tors. The RS-485 connections are made through con ven ient solderless screw terminals.

The LDM485 series is designed for full duplex op era tion over two-wire pairs. Outputs are tri-state, allowing multidropping of up to 64 units. Hardware hand shake is available over two separate wire pairs. Data rates are DC to 57.6k baud. Six diagnostic LED indicators are provided (see Figure 1) for in stal la tion guid ance and system trou bleshoot ing. The RS-232

SPECIFICATIONS

Model LDM485

Baud Rate Range 0 – 57.6K Baud Rate 57.6K 38.4K 19.2K 9.6K 4.8K 2.4K – 0

Distance (miles)

(1)

0.5 1 3 4 5 8

Distance (km) 0.8 1.7 5 6.7 8.3 13.3 Wire Capacitance Equal to 25pF per foot and up to 32 multidrop units Maximum

Multidrop Units 64 Common Mode Surge: 1500V

Isolation Continuous: 1000V Differential Mode (AC input)

Surge Protection ANSI/IEEE C37.90.1-1989 (9 devices) (all RS-485 inputs and outputs)

Modes Asynchronous 4-wire duplex, 2-wire half-duplex,

2-wire simplex

interface sup ports Request To Send, Clear To Send, Data Set Ready, Re ceived Line Signal Detect, and Data Ter mi nal Ready. A convenient null modem switch is pro vided for the data lines. Also, a line termination switch connects a line termination resistor and line bias re sis tors to the RS-485 receive lines. The RS-485 interface supports Request To Send and Clear To Send on separate wire pairs. The LDM485 may be used to convert two sets of send and receive channels by using RTS and CTS circuits as the second data channels. Data rates are the same. The units use 12VAC from a wall-mounted transformer to screw terminals 1 and 2 on the RS-485 con nec tor. Al ter nate ly, they can use ±12VDC to pins 9 (+) and 10 (–) of the RS-232 connector.

The LDM485 conforms to EIA RS-232 and RS-485 specifications. Data Ter mi nal Ready must be asserted by the host RS-232 port

before the LDM485 can transmit data. When Data Ter mi nal Ready is not as serted, all outputs of the LDM485 are high impedance, allowing up to 64 LDM485 units to be mul tidrop ped on a common com mu ni ca tions cable. See Figures 1 and 3 for details.

Request To Send and Clear To Send are carried through the RS-485 port as two separate wire pairs. These may be used for full duplex flow control.

Data Terminal Ready, DTR, must be asserted before the LDM485 can trans mit data. This is normally done by the host computer. For situations where the host equipment does not have the capability of supplying a DTR signal, RLSD may be used to automatically assert DTR. On the RS-232 connector P1 of each LDM485, simply connect RLSD pin 8 to DTR pin 20. This con nec tion is not ap pro pri ate for multi-drop installations.

Notes: (1) Distances reduced if multidropping more than 32 units; by 30% for 33-48 units, 50% for 49-64.

287

Basic Unit

LDM485-P, $287, shown smaller than actual size

Extended Warranty

Program

J-16

To Order

(Specify Model No.)

Power

Model No. Price RS232 Connector Source

LDM485-P $287 25 Pin male Host-powered

LDM485-S 287 25 Pin female Host-powered

LDM485-PT 305 25 Pin male Transformer

LDM485-ST 305 25 Pin female Transformer

Includes operator’s manual. Transformer powered units also include 120 Vac wall mount transformer.

Ordering Example: LDM485-ST converter: $305.

Notes: (2) TD = Transmit Data, RD = Receive Data, RTS = Request To Send, CTS = Clear To Send, DTR = Data Terminal Ready, DSR = Data Set Ready, RLSD = Received Line Signal Detect. (3) 120VAC and 220 VAC power transformers are available. (4) Ground-benign environmental conditions (no salt atmosphere, <50°C ambient temperature).

Model LDM485

Channel Lines

(2)

TD, RD, RTS, CTS

Control Lines

(2)

RTS, CTS, DTR, DSR, RLSD

Null Modem Switch 1 (Reverses RS-232 pins 2 and 3) RS-485 Output Drive 60mA max/output RS-485 Input

Impedance 12kΩ min/input Power:

AC operation

(3)

12VAC, ±10%, 10W screw terms 1 & 2

DC operation +11.5 to +17VDC @ 500mA on pin 9

-11.5 to -17VDC @ 100mA on pin 10

Operating 0°C to +70°C, 0-95% relative humidity, Environment noncondensing

Dimensions 53.3 mmH x 167.6 mmW x 32.5 mmD

(2.1 x 6.6 x 1.28")

Weight 200 g (7 oz) max

AC Transformer 311.8 g (11.0 oz) max

MTBF

(4)

>100,000 hrs

RS-232 P1 Pin Descriptions RS-485 P2 Pin Descriptions

Pin 1 Case Case Ground Pin 1 12VAC Pin 2 TD Transmit DataPin 2 PWR RTN Pin 3 RD Receive Data Pin 3 RTS A Pin 4 RTS Request To Send Pin 4 RTS B Pin 5 CTS Clear To Send Pin 5 CTS A' Pin 6 DSR Data Set Ready Pin 6 CTS B'

(connected to Data Pin 7 TD A

Terminal Ready) Pin 8 TD B Pin 7 Sig Gnd Signal Ground Pin 9 SIG RTN Pin 8 RLSD Receive Line Signal Detect Pin 10 RD A' Pin 9 +12VDC Positive DC Supply Input Pin 11 RD B' Pin 10 –12VDC Negative DC Supply Input Pin 12 SIG RTN Pin 16 Echo Sup Echo Suppression

(tie to pin 17 to enable) Pin 17 Echo Sup Echo Suppression

(tie to pin 16 to enable) Pin 20 DTR Data Terminal Ready

(connected to Data

Set Ready)