JED Communications Interfaces
- J995X & A: JED RS232 to RS485 (& RS422);
- J990: RS232 to 20mA converter;
- J994: Midi to RS232 converter;
- T462: Weigand to RS232.
1. JED RS232 to RS485 converter, J995X,
with automatic "TX connect-to-line" function for the transmitter, so it
does not need special driving software to transmit from a PC to a multi-drop
RS485 line. This is ideal for operation from Windows and other software
which has difficulty in accessing the driving logic behind the RTS line
drivers.
Links provide for baud rate selection, transmit byte length selection, RX line biasing, line termination, and optional RX blanking during transmission.
The transmitter can also be always enabled, so for 4-wire operation, with one pair always transmitting and one pair always receiving, a two way long distance data communications channel can be set up, equivalent to RS422 standards.
A data sheet is at: J995X.pdf . A close-up photo is at J995X.jpg .
2. JED J995A, our original RS232/RS485 converter, which uses the RS232 RTS line going HIGH to turn on the RS485 transmitter.
Links provide for RX line biasing, line termination, and optional RX blanking during transmission.
The data-sheet is at: J995A.pdf. The photo is at J995A.jpg.
(JED makes a number of other RS232 and TTL/CMOS to RS485 converters, with various power options and I/O options (B, C, D, E, F......) Call JED for specific requirements...we can probably do it.)
3. JED RS232 to 20mA isolator, J990, a bi-directional interface from a PC to a 20mA signalling loop. This is useful for interfacing to PLC and other industrial systems from a PC or terminal. While this is an old standard, it is still in occasional use, and JED still supports it with this box.
The data-sheet is at J990.pdf. A photo of the J990 is at J990.jpg.
4. J994 Midi to RS232 converter:
This takes RS232 signals (on a D9 connector) at 38400 baud and converts to an opto-isolated Midi signal at 31250 baud.
|
|
|
The three Midi connectors are standard Midi 5-pin DIN circular, with "Midi-In", "Midi-Out and "Midi-Thru" provided, allowing the usual daisy-chained Midi "network": This unit is housed in the same case as the PROM Programmer, but in black. All I/O lines are ESD protected and power input from a 9 to 15 volt DC plug pack powers the device. LEDs show the communications in and out for checking purposes.
5. T462 Communications/relay box as Wiegand to RS232 converter.
This device receives Wiegand contact closure bit streams and converts to an RS232 message.
Applications
are to interface an old-style magnetic key (encoded as a series of
pulses using embedded magnets) to an RS232 signal to feed into more
recent security or communications devices. (The Wiegand interface is
also used on more recent RFID and other scanners, as it is a standard
used in the security industry.) The T462 is shown on the JED projector
controller page. The case is 12.5cm (inc. connectors) by 5 cm by 2.5 cm.