User Manual for Assured 104-ICOM-2S Serial Communication Card

Quick Guide

This document provides instructions for the Assured 104-ICOM-2S and 104-COM-2S serial communication cards. Important: Always power off the computer before installing or removing the board or connecting/disconnecting field cabling to prevent damage and voiding warranties.

Product Overview

The 104-ICOM-2S is a serial communications board designed for PC/104 compatible computers, featuring two isolated serial data ports. The 104-COM-2S is the non-isolated version. Key features include:

• Multipoint transmission using RS422 or RS485 differential line drivers.
• Opto-isolation (on ICOM-2S) for protection against common mode noise.
• Support for 2-wire (Half-Duplex) and 4-wire (Full-Duplex) communication modes.
• Automatic transceiver control for RS485.
• 16-byte transmit/receive buffer (ST16C550 UART).

Specifications

• Serial Ports: Two shielded male D-sub 9-pin IBM AT style connectors.
• Data Rates: 50 to 115,200 baud (up to 460,800 as factory option).
• Isolation: 500 Volts (ICOM-2S).
• Operating Temperature: 0 to +60 °C (Industrial version: -30 to +85 °C).
• Power Required: +5VDC at 200 mA typical, 300 mA maximum.

Hardware Installation

1. Configure jumpers for options and base address before installation.
2. Remove power from the PC/104 stack.
3. Assemble standoff hardware.
4. Plug the board onto the PC/104 connector, ensuring proper pin alignment.
5. Install I/O cables.
6. Verify connections and power up the system.
7. Run the provided sample programs to validate installation.

Option Selection (Jumpers)

The board uses jumpers to configure settings:

• A5-A9: Set the board's base address on the I/O bus. Installing a jumper sets the bit to 0; no jumper sets it to 1.
• IRQ3-IRQ15: Set the interrupt level. One IRQ services both serial ports.
• 485A/B and 422A/B: Configure the port mode. Use 485 for 2-wire RS485 (Half Duplex) and 422 for 4-wire RS422 (Full Duplex).
• TRMI and TRMO: Connect on-board RC termination circuits. TRMI is for input lines (4-wire RS422); TRMO is for output/input lines (2-wire RS485).

Address Selection

The base address can be selected within the 000-3E0 hex range. Ensure the address does not overlap with other system functions. Use the provided FINDBASE.EXE program to identify available addresses.

Programming

The board uses standard 16550 UART registers. Initialization involves:

1. Setting the baud rate divisor (requires setting DLAB high at Base Address +3).
2. Setting the Line Control Register (Base Address +3) for word length, stop bits, and parity.
3. Setting the Modem Control Register (Base Address +4).
4. Flushing receiver buffers.

Reception can be handled via polling or interrupt-driven methods. Transmission in RS485 mode is automatic.

Connector Pin Assignments

The board uses 9-pin D-sub male connectors (P2 for COM A, P3 for COM B). Refer to the pinout table in the manual for specific RS422 and RS485 wiring configurations.