Model RS422AT-P RS422/485 Interface Card FEATURES � RS-422/485 Interface � Selectable Address � Two or Four Wire Operation � Short Slot � PC/XT/AT Compatible � 16450 UART DESCRIPTION This half size card can be installed in either long or For increased noise immunity, the communications short slots of ISA bus computers. This card can be used lines are loaded at the receiver and biased at the transmitter. for either RS-422 or RS-485 asynchronous serial A transmission line should be terminated at the receiving end in its characteristic impedance. Installing a jumper at communications. The card uses the 16450 type UART. a location marked LD on the card applies a 136W load It is 100% compatible with MS-DOS if the address is set to any COM 1 through COM 4 address. However, you across the input for RS-422 mode and across the transmit/ are not limited to only those addresses. Continuous receive input/output for RS-485 operation. When noise address selection can be setup anywhere in the I/O is a potential problem on long lines, the terminating resistance can be divided and the center point grounded by address range of 000 to 3FF hex. installing a jumper at a location marked LD GND on the A crystal controlled oscillator is located on the card. card. If needed, optional tranzorbs that limit very high This oscillator permits precise selection of baud rate from noise transients may be added on the I/O lines. 56 to 56,000 baud. For applications that require higher baud rates, the 16550 UART is available as a special 99 option. The transceiver used (type 75176) is capable of 470W %,$610KW driving extremely long communication lines at high baud rates. It is capable of driving up to 60mA on balanced 5;lines and receiving inputs as low as 200mV differential/’ signal superimposed on common mode noise maximum of 68W /’*1’-7V to +12V. The transceiver also features a thermal shutdown mode in case of communication conflict. 68W 5; 10KW %,$6470W 99 1 Document 1129, 8/28/97 Model RS422AT-P DESCRIPTION In RS-485 operations, where there can be as many as In addition to differential Transmit and Receive lines, 32 transmitters on a two-wire �party line�, only the RS- single-ended, buffered RTS and CTS line are provided on 485 ports at each end of the network should have the I/O connector. CTS must be pulled up to +5VDC for terminating resistors as described above. If the card is to the card to operate. If CTS won�t be controlled by have an ungrounded load, you can omit the LD GND software in your application, then you have two options. jumper mentioned above. Also, for RS-485 operation, You can install a jumper at the CTS jumper position on there must be a bias on the Rx+ and Rx- lines. The the card. You can also omit the jumper and install a RS422AT-P card can provide this bias if jumpers are jumper between pins 5 and 9 of the mating I/O connector. installed at locations marked +BIAS and -BIAS on the When the latter is done, you should check for proper card. installation of the communications cable. Full Duplex, Half Duplex, or Simplex operation can be selected by jumper options. SPECIFICATIONS Multipoint SOFTWARE Compatible with RS-422 and RS-485 A disk is provided that includes a graphical Set-up specifications. Up to 32 drivers and receivers program, and a routine titled FINDBASE that helps allowed on one line. select an I/O base address (if you are not using the Input Common Mode Voltage standard COM addresses) that will not conflict with other -7V to +12V resources already installed in the computer. Another Receiver Input Sensitivity software feature included is Windows DLLs that are –200mV designed to work with any Windows language that allows Driver Output calls to DLLs. These DLLs support Windows 3.1x, 60mA max Windows 95 and Windows NT. Baud Rate Operating Systems Supported 50 to 56K baud DOS 3.3 and higher Address Windows 3.1x Windows 95 Continuously mappable within 000 to 3FFF hex Windows NT Temperature Range Languages Supported Operating: 0 to 60�C QuickBASIC V4.5 Storage: -50 to +120�C Turbo C V2.0 Power Required Turbo Pascal V6.0 or higher +5VDC @ 400mA typical Demo/Example Programs Included Examples in C, and Pascal as well as Windows sample programs in C. PIN CONNECTIONS 576 &76ORDERING GUIDE 6LJQDO*QGModel RS422AT-P 9’&Board, Manual, Software 7; 5;7; 5;