ACCES I/O PRODUCTS INC 10623 Roselle Street, San Diego, CA 92121 TEL (858)550-9559 FAX (858)550-7322 MODEL ICOM-2S USER MANUAL FILE: MICOM-2S.
Notice The information in this document is provided for reference only. ACCES does not assume any liability arising out of the application or use of the information or products described herein. This document may contain or reference information and products protected by copyrights or patents and does not convey any license under the patent rights of ACCES, nor the rights of others. IBM PC, PC/XT, and PC/AT are registered trademarks of the International Business Machines Corporation. Printed in USA.
Warranty Prior to shipment, ACCES equipment is thoroughly inspected and tested to applicable specifications. However, should equipment failure occur, ACCES assures its customers that prompt service and support will be available. All equipment originally manufactured by ACCES which is found to be defective will be repaired or replaced subject to the following considerations. Terms and Conditions If a unit is suspected of failure, contact ACCES' Customer Service department.
Table of Contents Chapter 1: Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Multipoint Opto-isolated Communications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . COM Port Compatibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Line Bias and Termination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
List of Figures Figure 1-1: Figure 3-1: Figure 3-2: Figure A-1: ICOM-2S Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Simplified Schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ICOM-2S Option Selection Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Typical RS485 Two-Wire Multidrop Network . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1: Introduction The card is 10 inches long (264 mm) and should be installed in long slots of IBM PC/XT/AT or compatible computers. If installed in an eight-bit slot, the high interrupts (IRQ 10-15) will not be available to the ICOM-2S. Multipoint Opto-isolated Communications The ICOM-2S Serial Interface Card was designed for multipoint transmission on long communication lines in noisy environments using RS422 or RS485 differential line drivers.
ICOM-2S Manual Auto and Manual Transceiver Control RS485 communications requires the transmitter driver to be enabled and disabled as needed, to allow all cards to share the communications line. The ICOM-2S card has two methods to control the driver: automatic (Auto) and request to send (RTS) control. With automatic control, the driver is enabled when data is ready to be transmitted. The driver remains enabled for the transmission time of one character after data transfer is complete.
Specifications 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 NS16550. Transceivers used are type 75176. Serial Data Rates: 50 to 38,400 baud.(Optionally up to 230,400 baud with change in clock and opto isolators), Asynchronous, Type 16550 buffered UART. Address: Continuously mappable within 000 to 3FF (hex) range of AT I/O bus addresses.
ICOM-2S Manual Figure 1-1: ICOM-2S Block Diagram (Only one serial channel shown) 1-4 Manual MICOM-2S.
Chapter 2: Installation The software provided with this card is contained on either one CD or multiple diskettes and must be installed onto your hard disk prior to use. To do this, perform the following steps as appropriate for your software format and operating system. Substitute the appropriate drive letter for your CD-ROM or disk drive where you see d: or a: respectively in the examples below. CD Installation DOS/WIN3.x 1. 2. 3. 4. Place the CD into your CD-ROM drive.
ICOM-2S Manual To copy the files on the master diskette to your hard disk, perform the following steps. 1. Place the master diskette into a floppy drive. 2. Change the active drive to the drive that has the diskette installed. For example, if the diskette is in drive A, type ??? . 3. Type ???????? and follow the on-screen prompts. Directories Created on the Hard Disk The installation process will create several directories on your hard disk.
SAMPLES Samples for using ACCES32.DLL are provided in this directory. Using this DLL not only makes the hardware programming easier (MUCH easier), but also one source file can be used for both Windows 95/98 and WindowsNT. One executable can run under both operating systems and still have full access to the hardware registers. The DLL is used exactly like any other DLL, so it is compatible with any language capable of using 32-bit DLLs.
ICOM-2S Manual Findbase.exe DOS utility to determine an available base address for ISA bus , non-Plug-n-Play cards. Run this program once, before the hardware is installed in the computer, to determine an available address to give the card. Once the address has been determined, run the setup program provided with the hardware to see instructions on setting the address switch and various option selections. Poly.exe A generic utility to convert a table of data into an nth order polynomial.
To Install the Card 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Turn off computer power. Remove the computer cover. Remove the blank I/O backplate. Install jumpers for selected options from either the Option Selection of this manual or the suggestions of our ICOM2SET setup software program. Select the base address on the card for either the Address Selection of this manual or the suggestions of our FINDBASE setup software program. Install the card in an I/O expansion slot. Install the I/O cable.
Chapter 3: Option Selection The following paragraphs describe the functions of the various jumpers on the ICOM-2S card. Refer to the Figure 3-2, Option Selection Map for the locations of these jumpers on the card. CTS The CTS bit is used to indicate that the device connected to the ICOM-2S is ready to accept data from the ICOM-2S. Status can be tested by reading bit 4 of the MSR(modem status register) from the UART. The CTS line does not affect the operation of the card.
ICOM-2S Manual Simplex or Duplex The receiver can be set in either Simplex or Duplex by installing jumpers marked SX or DX. Simplex mode is intended for one-way communication able to transmit or receive. Duplex mode allows transmission or reception either simultaneous or alternatively as defined in the following paragraph. Full or Half-Duplex Full-Duplex allows simultaneous bi-directional communications and is selected by installing the FDX jumper.
Switches S1=COM-A Address S2=COM-B Address (This illustration has COM A at the COM 3 address, and COM B at COM 4 address.
Chapter 4: Address Selection The ICOM-2S base address can be selected anywhere within an I/O address range 100-3F8 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.
ICOM-2S Manual I/O bus address switches are marked A3-A9. The following table lists switch label vs. the address line controlled and the relative weights of each.
The following table lists standard DOS COM port addresses. Serial COM Port IRQ Base Hex Address COM1 IRQ 4 3F8 1 1 1 1 1 1 1 COM2 IRQ 3 2F8 1 0 1 1 1 1 1 COM3 IRQ 4 3E8 1 1 1 1 1 0 1 COM4 IRQ 3 2E8 1 0 1 1 1 0 1 A9 Address Switch Settings A8 A7 A6 A5 A4 A3 Table 4-4: Standard COM Port Addresses Notice that only two interrupts are assigned to four serial ports. "Sharing" interrupts is not a good idea if both ports are used at the same time. Manual MICOM-2S.
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Chapter 5: Programming Sample Programs There are sample programs provided with the ICOM-2S card in C, Pascal, QuickBASIC, and several Windows languages. DOS samples are located in the DOS directory and Windows samples are located in the WIN32 directory. Windows Programming The ICOM-2S card installs into Windows as COM ports. Thus the Windows standard API functions can be used. In particular: ? ? CreateFile() and CloseHandle() for opening and closing a port.
ICOM-2S Manual On the ICOM-2S card, the clock frequency to the UART is 1.843 MHz.
The C command to set the UART for an 8-bit word, no parity, and one stop bit is: outportb(BASEADDR +3, 0x03) The third step of the initialization sequence is to set the Modem Control Register at Base Address +4. This register controls functions on some cards. Bit 1 is the Request to Send (RTS) control bit. This bit should be left low until transmission time. (Note: When operating in the automatic RS485 mode, the state of this bit is not significant.) Bits 2 and 3 are user-designated outputs.
ICOM-2S Manual 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. The following software example is for non-AUTO operation. First the RTS line should be set high by writing a 1 to Bit 1 of the Modem Control Register at Base Address +4. The RTS line is used to toggle the transceiver from receive mode to transmit mode and vice versa.
Chapter 6: Connector Pin Assignments The popular 9-pin D subminiature connector is used for interfacing to communication lines. The connector is equipped with 4-40 threaded standoffs (female screw lock) to provide strain relief. Pin No.
Appendix A: Application Considerations Introduction Working with RS422 and RS485 devices is not much different from working with standard RS232 serial devices and these two standards overcome deficiencies in the RS232 standard. First, the cable length between two RS232 devices must be short; less than 50 feet at. Second, many RS232 errors are the result of noise induced on the cables.
ICOM-2S Manual A balanced differential line receiver senses the voltage state of the transmission line across the two signal input lines. If the differential input voltage is greater than +200 mV, the receiver will provide a specific logic state on its output. If the differential voltage input is less than -200 mV, the receiver will provide the opposite logic state on its output. A maximum operating voltage range is from +6V to -6V allows for voltage attenuation that can occur on long transmission cables.
RS485 Data Transmission The RS485 Standard allows a balanced transmission line to be shared in a party-line mode. As many as 32 driver/receiver pairs can share a two-wire party line network. Many characteristics of the drivers and receivers are the same as in the RS422 Standard. One difference is that the common mode voltage limit is extended and is +12V to -7V.
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