• Fast auto TX-enable RS232 to RS485 interface converter for 2-wire, half-duplex communications, at distances up to 4000 ft. and data rates up to 115.2Kbps (with short data strings).
• Recommended for special applications only in port powered mode. Full RS485 operation with optional 9VDC power supply.
• Choose from two different models.
GENERAL DESCRIPTION and TYPICAL APPLICATIONS:
The LP24FT/FR is a fast Async bi-directional RS232 to RS485 interface converter for 2-wire, half-duplex applications, with an automatic TX enable circuit, that will operate at data rates up to 115.2Kbps (with short data strings in the port powered mode). The Model LP2FT has a removable screw terminal strip that will accommodate 14-26AWG wire on the RS485 side of the interface. The Model LP24FR provides an RJ11/12 connector for RS485 connections.
The LP24FT/FR is designed for office and/or indoor applications (non-isolated). Can be used for point to point, or multi-drop 2-wire systems. When used with an external 9VDC power supply (optional) the unit will operate per the RS485 specification; however, in port powered mode some restrictions apply. Bias and Termination jumpers are provided for powered operation.
Special notes: Even though our unique port-powered deign is very power efficient, we do NOT generally recommend port powered devices, because of potential problems with the limited power available from a typical RS232 port. Just the characteristic impedance of the cable can load down the transmitted signals to a remote device. If strings are limited to short bursts (depending on baud rate) extended distances can be achieved. Long string cause the onboard capacitance to discharge into the load/line and the signal strength degrades with time. In many applications over short distances (up to about 50 ft.) good operation can be expected. It is generally not possible to add termination in port powered applications. Light on-board bias resistors are provided (22K).
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LP24FT(FR).pdf | Converter schematic |
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PHYSICAL PROPERTIES and FEATURES:
| RS232 | 3-wire interface to RJ11/12 Connector (TX, RX, Common). |
| RS485 | Optional 3-position removable screw terminal strip or RJ11/12 connector. |
| Power | RS232 Port powered (RTS, DTR) high state +7V, or optional 9VDC external |
| LEDs | None (See ASC24W, ASC24R, and ASC24T powered units) |
| Bias | 22K Ohm pull-up and pull-down (fixed) and, 620 Ohm pull-up and pull-down (jumper selectable) for external powered applications. |
| Termination | 120 Ohm (jumper selectable) |
| Special | 25-Pin D-Sub female connector in protective shell. |
| Protection | None (See ASC24W, ASC24R, and ASC24T powered units) |
SPECIFICATIONS:
| Distance | RS485 up to 4000 ft. (1250 meters) |
| Operation | 2-wire half-duplex RS485 |
| Format | Asynchronous data with any combination of bits, parity, stop (auto mode) |
| Speed | Up to 115.2Kbps |
| Temperature | 0-65C (32-150F) ambient |
| Humidity | 10-90% non-condensing |
| Voltage | +7V minimum on RTS and/or DTR |
| Power | Under 1/8 Watt (typical) + external load |
| Size | 3.35” X 2.2” X 0.95” board, shell and connectors |
OPTIONS AND ORDERING INFORMATION:
| LP24FT | $49.00 ea. (Circuit board with shell and removable screw terminals) |
| LP24FR | $49.00 ea. (Circuit board with shell and RJ11/12 connector) |
| Supply | $8.50 ea. (12VDC @ 200/300 mA wall power supply) |
| *LP24FT with all options (DB9F cable): LP24FR-PS @ $57.50 ea. (Qty. 1-9) |
| *LP24FR with all options (DB9F cable): LP24FR-PS @ $57.50 ea. (Qty. 1-9) |
Please call us at: 513-874-4796
 Contact Information:R.E. Smith 10330 Chester Rd., Cincinnati, Ohio 45215 Phone: 513-874-4796 Fax: 513-874-1236 |