HIGH SPEED DUAL ASYNCHRONOUS SERIAL BOARD INTRODUCTION ABOUT YOUR SERIAL BOARD Congratulations on your purchase of the dual serial board! It combines the convenience of two serial port connectors, each incorporating a 16550AN UART, with throughput capability of up to 57.6K bits per second (bps). Your serial board is a 100% IBM PC-compatible, internal half card, equipped with two DB-9 (9-pin) serial port connectors labeled Channels A and B. It can be used for modems, printers, mouse devices and other serial equipment. CABLE REQUIREMENTS You'll need two RS-232 cables to connect two serial devices to the serial board. Use shielded cables to ensure minimal interference with radio and television reception. The ports on your serial board each require a DB-9 female (socket) connector at one end of each cable. Check your peripheral devices to determine what types of connectors they require at the other end. Two common RS-232 connectors are DB-9 and DB-25 female or male (plug). Your local distributor should be able to supply you with the proper cable. We recommend that your cable length not exceed 6 feet. PRE-INSTALLATION SELECTING COM PORTS Each port on your serial board requires a serial port address: COM1, COM2, COM3, or COM4. The board's factory settings are COM1 for the Channel A port and COM2 for the Channel B port. If you already have a serial device at COM1 and/or COM2 on your computer, you will need to use the address(es) COM3 and/or COM4 for the new serial ports. To assign the new COM port address(es), you'll need to change the COM port jumper switches that are illustrated in Figure 1, J1 through J4. Each COM port jumper has three upright contacts, and a shunt over two of the contacts sets the switch for that COM port. In Figure 1, the dark areas in the expanded view of J1 and J2 indicate which contacts are covered when the board is shipped. For Channel A, the shunt is over the left and center contacts of the COM1 switch. For Channel B, the shunt is over the right and center contacts of the COM2 switch. [FIGURE 1 DIAGRAM HERE] If you have to change a factory-set COM port because you already have one or two serial devices installed, you may also have to change the corresponding Interrupt Request (IRQ). Software such as communications programs and printer drivers use IRQs to instruct the computer to stop the processor's current operation in order to perform other operations. WARNING: In order to set up your serial operations without conflicting IRQs, review the following information before you change a COM port or IRQ. You may also need to review your application software manual to find out which COM ports and IRQs your software supports. There are five possible IRQs for each port/channel on the serial board: IRQs 2 through 5 and IRQ7, labeled I2, I3, and so on. Each IRQ jumper switch has two contacts, with a shunt covering (and thereby enabling) the selected IRQ. SELECTING AN INTERRUPT REQUEST (IRQ) IBM-compatible computers reserve IRQ4 for COM1 and IRQ3 for COM2, as shown in the table below. All IBM PC-compatible programs and device drivers support these reserved IRQs for those two serial ports. Serial Serial Port Port IRQ Address (Hex) ---- ---- ------- COM1 IRQ4 3F8-3FF COM2 IRQ3 2F8-2FF COM3 IRQ4 3E8-3EF COM4 IRQ3 2E8-2EF If you need to use COM3 or COM4, you may be able to use IRQ4 or IRQ3, as shown in the table. However, keep the following information in mind. 1. To select COM3 or COM4, lift the shunt off the switch of the COM port you want to change, and replace it over the two corresponding contacts of your selected COM port. NOTE: Be sure that the Channel A jumper shunt covers the left and center contacts, and that the Channel B jumper shunt covers the right and center contacts. When you are finished, one jumper should be to the left, the other to the right. 2. To enable a different IRQ, lift the Channel A or Channel B shunt off the IRQ you are changing, and replace it over the two contacts of your selected IRQ for that channel. Do not enable two IRQs for the same channel. 3. To disable an IRQ because it isn't needed, lift the shunt off the switch of the enabled IRQ. Replace the shunt so that it straddles one pin each of two adjacent IRQs. for example, I4 and I5. This does not make any connection, but keeps the shunt handy in case you wish to enable an IRQ for that serial port again. TROUBLESHOOTING If a device that you have attached to the serial board is not working properly, try the following: 1. Attach the device to a serial port other than one on the dual serial board to make sure that the problem is not with the device. 2. If your device was previously attached to a different serial port, you may have to change your device's software setup to reflect its new COM port address and IRQ. 3. If problems occur while using high throughput speeds, make sure the RS-232 cable does not exceed 6 feet. 4. If you still encounter problems, review the previous information on selecting COM ports and IRQs. You may find conflicting COM port addresses or IRQs. Review the software parameters you have set, also, to be sure you specified the correct COM ports. DB-9 PIN ASSIGNMENTS The following chart shows the pin assignments and signal source for a DB-9 connection to your serial board. Function DB-9 Signal Source ------------------- ---- -------------- Transmitted Data 3 Computer Received Data 2 Serial Device Request to Send 7 Computer Clear to Send 8 Serial Device Data Set Ready 6 Serial Device Signal Ground 5 Both Directions Carrier Detect 1 Serial Device Data Terminal Ready 4 Computer Ring Indicator 9 Serial Device