1.0 GENERAL DESCRIPTION

The Model 253 is an interface converter that allows users to link RS-232 and RS-422 equipment. The Model 253 comes equipped with DTE/DCE switch and either screw terminals or RJ-11 modular connector for the RS-422 differential input and output.

2.0 SPECIFICATIONS

2.1 Interface - RS-232: Pins 3 and 2 transmit and receive data; Pin 7 connected to Pin 8; Pins 1,4 and 6 connected together; Pin 5 signal ground. RS-422: T+ and T- Transmit Data, R+ and R- Receive Data.

2.2 Connectors
RS-232 - Female DB9 pin.
RS-422 - Screw terminals or modular phone jack, RJ-11.

2.3 Data Rate - 0 to 19,200 BPS.

2.4 Transmission - Asynchronous full duplex over 4 wires (2 twisted pair).

2.5 Power
2.5.1 Derived Power from interface. If any of the pins 1,4,6,7 or 8 are high the 253 will take power from that pin. The energized pin must be at least +5.0 volts.
2.5.2 If there are no control signal then power is derived from the data input pin. The data input pin must be at least -5.0V in the quiescent state with the Model 253 connected.

2.6 Size - 1.3"W X 3"L X .75"H.

2.7 Environment - 0° to 50° C, 5% to 95% relative humidity , non-condensing.

3.0 INSTALLATION

The Model 253 is designed to interface RS-232 with RS-422 4 wire devices.

The user must determine if the Model 253 will look like a DCE or a DTE device. When configured as a DCE the 253 will connect to a DTE device such as a PC or terminal. When set as DTE the 253 will connect to a DCE device such as a modem. Pin configuration for the RJ-11 is shown below.

4.0 OPERATION

The Model 253 is configured as a RS-232 to RS-422 interface converter and as such the unit will perform full duplex conversion of the TD and RD signals. The RS-422 equipment gets connected to the Model 253T through the 4 position terminal block and the 253P through the RJ-11 connector. The R+ and R- are the receiver input into the Model 253 and T+ and T- are the transmitter outputs. When connecting the Model 253 to RS-422 equipment, the T+ and T- should be members of one twisted pair while R+ and R- should be members of the other.

When the RS-232 input signal is - or marking the T- lead will be high and the T+ will be low. To cause the RS-232 output signal to be - or marking the R- should be brought high and the R+ should be low.

5.0 TROUBLESHOOTING

Operation can be verified if one of the devices to which the modems are attached is capable of operating in a full duplex mode (such as terminal). Connect the 253 to the terminal via the RS-232 connector and make the following connections at the analog interface. (Set DTE/DCE switch to DCE).

If the modem is functioning any data entered on the key-board should appear on the screen.

6.0 CONNECTOR PIN ASSIGNMENTS

7.0 POWER

The Model 253 derives its power from any of the control signal pins 1,4,6,7 or 8, or from the data input pin. For proper operation one of these pins must be at lease -5.0 Volts in the quiescent state. This criteria is usually met by the Transmit Data signal, which will appear on pin 2 or 3, depending on the position of the DTE/DCE switch.

8.0 HELP

Assistance can be obtained by visiting our Technical Support Center.
 

Warranty

Telebyte warrants the equipment to be free from defects in material and workmanship, under normal and proper use and in its unmodified condition, for 12 months, starting on the date it is delivered for use. TELEBYTE's sole obligation under this warranty shall be to furnish parts and labor for the repair or replacement of products found by TELEBYTE to be defective in material or workmanship during the warranty period. Warranty repairs will be performed at the point of manufacture. Equipment approved for return for warranty service shall be returned F.O.B. TELEBYTE factory and will be redelivered by TELEBYTE freight prepaid, except for non- continental U.S.A. locations. These deliveries will be sent COD freight and import/export charges.

THE ABOVE WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, STATUTORY OR OTHERWISE, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TELEBYTE SHALL NOT BE LIABLE FOR ANY DAMAGES SUSTAINED BY RESELLER OR ANY OTHER PARTY ARISING FROM OR RELATING TO ANY EQUIPMENT FAILURE, INCLUDING, BUT NOT LIMITED TO CONSEQUENTIAL DAMAGES NOR SHALL TELEBYTE HAVE ANY LIABILITY FOR DELAYS IN REPLACEMENT OR REPAIR OF EQUIPMENT.

Out of warranty equipment may be returned to the Greenlawn, NY customer service facility prepaid as described above. Return shipping charges will be billed to the customer. The repaired unit will have a 90 day warranty. In those cases where "NO TROUBLE" is found, a reduced charge will be billed to cover handling, testing and packaging.

Whether in or out of warranty a Return Material Authorization number (RMA) is necessary. Assistance can be obtained by visiting our Technical Support Center.

Document No. 0315-0159/Rev. B

Model	Product Info
253