Measurement COM2328AT User Manual

COM232/8AT

Eight Channel Asynchronous Serial Communications Adapter
User’s Guide
IOtech, Inc.
Fax: (440) 439-4093
●●●●
p/n 1000-0901 rev 1.1, March 1998
Released per EO# 2053R5
●●●●
Cleveland, Ohio 44146
●●●●
e-mail: sales@iotech.com
●●●●
(440) 439-4091
●●●●
http://www.iotech.com

Contents

Overview ..........................................................................................................................................3
Specifications .................................................................................................................................3
Addressing.......................................................................................................................................4
Interrupts ..........................................................................................................................................5
Scratchpad or Interrupt ID Register Selection ..............................................................................5
Output Configurations ....................................................................................................................7
Register Definitions.........................................................................................................................8
Interrupt Enable Register.........................................................................................................8
Interrupt Identification Register ..............................................................................................9
FIFO Control Register ............................................................................................................10
Line Control Register .............................................................................................................11
MODEM Control Register.......................................................................................................12
Line Status Register...............................................................................................................13
MODEM Status Register.........................................................................................................14
Scratchpad Register (Interrupt ID Register not accessible)...............................................14
Interrupt ID Register (Scratchpad Register not accessible)...............................................14
FIFO Interrupt Mode Operation.....................................................................................................15
Divisor Latch Settings for Common Baud Rates........................................................................15
TM
Installation for Systems with Windows95
Installation for Systems with WindowsNTTM Version 4.0 ...........................................................18
................................................................................16

Warranty

Your IOtech warranty is as stated on the product warranty card. You may contact IOtech by phone, fax machine, or e- mail in regard to warranty-related issues. Phone: (440) 439-4091, fax: (440) 439-4093, e-mail: sales@iotech.com
Limitation of Liability
The COM232/8AT has been thoroughly tested and the documentation reviewed. However, IOtech does not warrant the performance of the product for any particular purpose. In no event is IOtech liable for any damages resulting, directly or indirectly, from the use of this product.
ESD Caution
This ESD caution symbol urges proper handling of equipment or components sensitive to damage from electrostatic discharge. Proper handling guidelines include the use of grounded anti-static mats and wrist straps, ESD-protective bags and cartons, and related procedures.
Copyright Notice
COM232/8AT documentation and printed circuit board are copyright with all rights reserved by IOtech, Inc., Cleveland, Ohio, USA. No part of this product may be copied, reproduced or transmitted by any mechanical, photographic, electronic or other method without prior written consent of IOtech, Inc. Copyright © IOtech Inc. 1997, All Rights Reserved. IOtech, Inc. 25971 Cannon Road, Cleveland, Ohio 44146 COM232/8AT is a trademark of IOtech, Inc.
2 COM232/8AT User’s Guide March 1998 1000-0901, rev 1.1

Overview

The COM232/8AT eight-channel asynchronous serial communication adapter is designed to be 100 percent compatible with the IBM PC/AT. Eight phone jacks (RJ-11 connectors) are used for making external connections.
The serial interface is made through eight 16550 Asynchronous Communication Elements (ACEs). 16550 ACEs are compatible with 8250 ACEs used in IBM PC, PC/XT, and compatible computer models. In addition, the 16550 ACEs are 16450 compatible while offering a FIFO mode. This additional mode can be invoked to reduce overhead in the CPU. The FIFO mode increases performance by providing a 16-byte transmit FIFO and one 16-byte receive FIFO. These two FIFOs buffer data, thereby reducing the number of interrupts issued to the CPU.
Other features of the 16550 ACE include:

Specifications

Bus Interface: IBM compatible 16-bit bus Dimensions: 8” x 4.8” Controllers: Eight 16550 Asynchronous Communication Elements Channels: Eight, numbered 1 through 8 External Connections: Type RJ-11 phone jack connectors Transmit Drivers: MC1488, or compatible Receive Buffers: MC1489, or compatible I/O Address Range: 0000 - FFFF hex Interrupt Levels: 2 thru 7, 10 thru 12, 14 thru 15
Programmable baud rate, character length, parity, and the number of stop bits.
Automatic addition and removal of start, stop, and parity bits.
Independent and prioritized transmit, receive and status interrupts.
Power Requirements:
I
T
494 mA +5 Volts 56 mA +12 Volts 58 mA - 12 Volts
I
is the typical adapter current value.
T
Supply
1000-0901, rev 1.1 March 1998 COM232/8AT User’s Guide 3
Addressing
The COM232/8AT uses eight I/O address locations per port. Full 16-bit address decoding allows base address selections in the range: 0000 to FFFF Hex. Two DIP switches, designated SW1 and SW2, are used to specify the adapter’s base address as follows:
SW1 determines the address setting for A15 through A10.
SW2 determines the address setting for A9 through A6.
The adapter uses the remaining address inputs to determine the channel and register being used.
The address of each port is incremented by a factor of 8 (in hexadecimal code) from the base address. For this reason, 64 address locations are used, as indicated by the table at the right. Note that SW1, SW2, and other component locations can be referenced on the figure, COM232/8AT Layout Reference, on page 6.
Port Range Port Range
10
28
316
424
64 Address Locations
7 5 32
thru
15 6 40
thru
23 7 48
thru
31 8 56
thru
thru
thru
thru
thru
39
47
55
63
The following three figures serve as sample switch settings. Note that there are 6 “hidden” settings, each with a fixed value of zero. These hidden settings have been included in the following illustrations.
4 COM232/8AT User’s Guide March 1998 1000-0901, rev 1.1

Interrupts

The COM232/8AT is capable of supporting 11 interrupt levels (IRQ 2 thru IRQ 7, IRQ 10 thru IRQ 12, IRQ 14, and IRQ 15). All channels share the same interrupt. You can change the interrupt selection by repositioning the jumper on JP9. The interrupt positions for JP9 are indicated in the figure, COM232/8AT Layout Reference, on page 6.

Scratchpad or Interrupt ID Register Selection

Jumper JP10 is used to select the Scratchpad Register, or the Interrupt ID Register. The JP10 setting to be used is based on the operating system and the software interfacing with the COM232/8AT. The following table indicates settings for Windows95 and WindowsNT, version 4.0 applications.
System JP10 Setting
Windows95
WindowsNT, version 4.0
Note: The Scratchpad and Interrupt ID registers are discussed in more detail on page 14.
Note: Do not confuse the Interrupt ID Register with the Interrupt Identification Register.
Scratchpad
Interrupt ID
1000-0901, rev 1.1 March 1998 COM232/8AT User’s Guide 5
6 COM232/8AT User’s Guide March 1998 1000-0901, rev 1.1
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