0623 Roselle Street, San Diego, CA 92121 y (858) 550-9559 y Fax (858) 550-7322 contactus@accesio.com y www.accesio.com MODEL 104-ICOM-2S AND 104-COM-2S USER MANUAL FILE: M104-ICOM-2S.
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Table of Contents Chapter 1: Introduction ......................................................................................................... 5 Figure 1-1: Block Diagram............................................................................................................................. 6 Specification...................................................................................................................................................... 7 Chapter 2: Installation...................
Chapter 1: Introduction This serial communications board is designed for use in PC/104 compatible computers. Two isolated serial data ports are provided on the board. Model COM-2S is simply a non-isolated version of the ICOM-2S. Multipoint Opto-isolated Communications The board allows for multipoint transmission on long communication lines in noisy environments using RS422 or RS485 differential line drivers.
PC/104 BUS +5V OPTO-ISOLATED Figure 1-1: Block Diagram 6 Manual 104-ICOM-2S, 104-COM-2S
Specification Communications Interface • Serial Ports: Two shielded male D-sub 9-pin IBM AT style connectors compatible with RS422 and RS485 specifications. Serial communications ACE used is type ST16C550. Transceivers used are type 75176. • Serial Data Rates: 50 to 115,200 baud. 460,800 baud as a factory installed option. Asynchronous,Type 16550 buffered UART. • Address: Continuously mappable within 000 to 3FF (hex) range of AT I/O bus addresses.
Chapter 2: Installation A printed Quick-Start Guide (QSG) is packed with the board for your convenience. If you’ve already performed the steps from the QSG, you may find this chapter to be redundant and may skip forward to begin developing your application. The software provided with this PC/104 Board is on CD and must be installed onto your hard disk prior to use. To do this, perform the following steps as appropriate for your operating system.
Installing the Hardware Before installing the board, carefully read Chapter 3 and Chapter 4 of this manual and configure the board according to your requirements. The SETUP Program can be used to assist in configuring jumpers on the board. Be especially careful with Address Selection. If the addresses of two installed functions overlap, you will experience unpredictable computer behavior. To help avoid this problem, refer to the FINDBASE.EXE program installed from the CD.
To add a COM port, use START|CONTROL PANEL|PORTS applet and click ADD, then enter the correct UART address and Interrupt number. When the “Add New Port” dialog is configured click OK, but answer “Don’t Restart Now” when prompted, until you’ve added any other ports as well. Then restart the system normally, or by selecting “Restart Now.
Click the “View or change resources for this hardware (Advanced)” link. Click the “Set Configuration Manually” button. Select “Basic Configuration 8" from the “Settings Based on:” drop-down list. Select “I/O Range” in the “Resource Settings” box and Click the “Change Settings...” button.
Select “IRQ” in the “Resource Settings” box and Click the “Change Settings” button. Enter the IRQ of the board and Click “OK”. Close the “Set Configuration Manually” dialog and Click “Finish.” Click “Do Not Reboot” if you wish to install more ports. Repeat all of the above steps, entering the same IRQ but using the configured Base address for each additional UART. When you are done installing ports, reboot the system normally.
Chapter 3: Option Selection The following paragraphs describe the functions of the various jumpers on the board. A5 through A9 Place jumpers at locations A5 through A9 to set the board's base address on the I/O bus. Installing a jumper sets that bit to a zero, while no jumper will leave the bit a one. See chapter 4 of this manual for more details on selecting an available I/O address.
Terminations and Bias A transmission line should be terminated at the receiving end in its characteristic impedance. Installing a jumper at the location labeled TRMO applies a 120Ω load in series with a 0.01μF capacitor across the output for RS422 mode and across the transmit/receive output/input for RS485 operation. A jumper at the TRMI location applies a load on RS422 inputs. +5 VDC 620 TRx+ +5 VDC 620 100 pF Rx+ Tx+ 0.01 : F 100 pF 120 100 pF 0.01 : F 0.
Communication Modes and Cabling Options Cable Mode Simplex Simplex HalfDuplex Full-Duplex 2-wire Receive Only 2-wire Transmit Only 2-wire 4-wire w/o local echo 15 Board A Board B Pins Pins Rx- 1 2 Rx+ 9 3 Tx+ 2 9 Tx- 3 1 TRx+ 2 2 TRx- 3 3 Tx+ 2 9 Tx- 3 1 Rx- 1 3 Rx+ 9 2 Manual 104-ICOM-2S, 104-COM-2S
Chapter 4: Address Selection The board’s base address can be selected anywhere within the I/O bus address range 000-3E0 hex, providing that the address does not overlap with other functions. If in doubt, refer to the table below for a list of standard address assignments. (The primary and secondary binary synchronous communication ports are supported by the Operating System.
Board Address jumpers are marked A5-A9. The following table lists jumpers name vs. the address line controlled and the relative weights of each.
Chapter 5: Programming A total of 32 consecutive address locations are allocated to the board, 17 of which are used. The UARTs are addressed as follows: Table 5-1: Address Selection Table I/O Address Read Write Base +0 thru 7 COM A UART COM A UART Base +8 thru F COM B UART COM B UART Base +10h Board IRQ Status N/A Base +11 thru 1F N/A N/A The Read / Write registers for the UARTs match the industry-standard 16550 registers. The Board IRQ status register is compatible with Windows NT.
Initialization Initializing the chip requires knowledge of the UART's register set. The first step is to set the baud rate divisor. You do this by first setting the DLAB (Divisor Latch Access Bit) high. This bit is Bit 7 at Base Address +3. In C code, the call would be: outportb(BASEADDR +3,0x80); You then load the divisor into Base Address +0 (low byte) and Base Address +1 (high byte).
Bit 2 determines the number of stop bits. There can be either one or two stop bits. If Bit 2 is set to 0, there will be one stop bit. If Bit 2 is set to 1, there will be two stop bits. Bits 3 through 6 control parity and break enable. They are not commonly used for communications and should be set to zeroes. Bit 7 is the DLAB discussed earlier. It must be set to zero after the divisor is loaded or else there will be no communications.
Transmission RS485 transmission is simple to implement. The AUTO feature automatically enables the transmitter when data is ready to send so no software enabling procedure is needed.
Chapter 6: Connector Pin Assignments The popular 9-pin D subminiature connector (male) is used for interfacing to communication lines. The connectors are equipped with 4-40 threaded standoffs (female screw lock) to provide strain relief. The connector labeled P2 is for COM A, and P3 is COM B. Table 6-1: P2/P3 Connector Pin Assignments Pin No.
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