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®
Serial Communications
COMT 366 Series
RS-232 to RS-485 Converter
with LCD, 38.4 kbps Data Rate
COMT 366M: DB-25M Connector
COMT 366F: DB-25F Connector
USER’S MANUAL
VER. D • OCT 2001
No part of this manual may be reproduced without permission
®
CyberResearch , Inc.
www.cyberresearch.com
25 Business Park Dr., Branford, CT 06405 USA
203-483-8815 (9am to 5pm EST) FAX: 203-483-9024
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® CyberResearch Serial Communications COMT 366 Series ©Copyright 2001 All Rights Reserved. October 15, 2001 The information in this document is subject to change without prior notice in order to improve reliability, design, and function and does not represent a commitment on the part of CyberResearch, Inc. In no event will CyberResearch, Inc. be liable for direct, indirect, special, incidental, or consequential damages arising out of the use of or inability to use the prod
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® COMT 366 Series CyberResearch Serial Communications COMT 366 Series iv ©Copyright 2001 CyberResearch, Inc.
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® CyberResearch Serial Communications COMT 366 Series FCC Information WARNING: This equipment generates, uses, and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual, may cause interference to radio communications. It has been tested and found to comply with the limits for class A computing devices pursuant to Subpart B of Part 15 of FCC Rules, which are designed to provide reasonable protection against such interference when oper
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® COMT 366 Series CyberResearch Serial Communications 1.0 General Description............................ 1 1.1 The LCD.................................................................................... 1 2.0 Specifications....................................... 3 2.1 Interface ................................................................................... 3 2.2 Connectors .............................................................................. 3 2.3 Data Rate............
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® CyberResearch Serial Communications COMT 366 Series 1.0 General Description The COMT 366 converter provides a convenient method of interfacing EIA-232-based equipment with an RS-485 network using a half-duplex, single twisted-pair transmission protocol. The COMT 366 provides the capability for a high-speed, low cost, local area network. Up to 32 users can be supported at rates up to 38.4K Baud and total separations of 6,000 feet. The LCD feature assists with installation and troublesh
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® COMT 366 Series CyberResearch Serial Communications If the transmit signal is in the quiescent state (continuously low) only the lower segments and the vertical bar will be illuminated. This indicates a constant negative state. If the transmit or receive inputs to the device were streaming, i.e., in the positive mode continuously, the LCD display would show the vertical segment and the upper segments only. For those cases where there is valid data transmission, both the upper and low
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® CyberResearch Serial Communications COMT 366 Series 2.0 Specifications 2.1 Interface Conforms to EIA RS-232 and RS-485 specifications. 2.2 Connectors Five-position terminal block. 2.3 Data Rate 0 to 38.4 KBPS 2.4 Switches DTE/DCE selector switch: allows reversing of Pins 2 and 3 of EIA-232 connector. Four-position dip switch: two switches set operating mode, two switches set cable termination value. 2.5 Indicators Equipped with an LCD display for data, five control
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® COMT 366 Series CyberResearch Serial Communications 3.0 Installation The COMT 366 is designed to interface EIA-232 with RS-485 equipment. The EIA-232 device can be either a DTE or DCE type device. The DTE/DCE selector switch allows for reversing Pins 2 and 3 ( TD and RD), thereby eliminating the need for null modem cables. If the switch is in the DTE position, Pin 2 of the RS-232 connector is an output for the COMT 366. The half-duplex nature of RS-485 allows for a Master-Slave c
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® CyberResearch Serial Communications COMT 366 Series 4.0 Operation Operation in an RS-485 environment requires all devices attached to the network to have some level of intelligence in order to establish an orderly flow of data on the single twisted pair. The COMT 366 offers three possibilities for hardware data flow control. The user selects the mode which avoids the contention problem. Unless contention is resolved, there is the possible collision of data caused by two devices attemp
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® COMT 366 Series CyberResearch Serial Communications 4.1 Termination of the Line There are four user-selectable resistive terminating values which are implemented using switches A and B of the dipswitch. As the length of the transmission cable and the number of users increases, the chosen value becomes more critical to error-free operation. Typically, devices at the end of a long bus are terminated and units multi-dropped between the ends are not terminated. The cable used to connec
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® CyberResearch Serial Communications COMT 366 Series 5.0 Troubleshooting The following is a list of possible problems that may arise during the installation and solutions to those problems: 1. The data being received is garbled. a) The DTE/DCE switch is not set properly (see Section 3.0, "Installation"). On the COMT 366, observe the LCD and verify that TD and RD are shown as low in the quiescent state (see Section 1.1, "The LCD"). b) The equipment that the COMT 366 is connected t
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® COMT 366 Series CyberResearch Serial Communications The converter may now be tested by setting the following switches: DCE on COMT 366 DTE Dip Switch 1 ON 2 OFF 3 OFF 4 ON If the converter is functioning correctly, any data entered on the keyboard of the terminal should appear on the screen and the TD and RD indicators should flash indicating the flow of data. 8 ©Copyright 2001 CyberResearch, Inc.
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® CyberResearch Serial Communications COMT 366 Series 6.0 RS-232 Pin Number Assignments Pin EIA Name CCITT 2 BA 103 Transmit Data * 3 BB 104 Receive Data * 4 CA 105 Request to Send ** 5 CB 106 Clear to Send ** 6 CC 107 Data Set Ready *** 7 AB 102 Signal Ground Gnd 8 CF 109 Data Carrier Detect *** 20 CD 108.2 Data Terminal Ready *** * These signals can be reversed using the selector switch. **, *** Connected together CyberResearch, Inc.
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® COMT 366 Series CyberResearch Serial Communications 7.0 Power The COMT 366 can be either host or self powered. In the self-powered mode, a wall- mounted transformer supplies low voltage AC and the required +12, -12, and +5 Volts are generated internally. For COMT 366, supply +12 volts on Pin 9. 7.1 COMT 366 The COMT 366 is powered by a small, wall-mounted transformer that supplies 12 VDC @ 500 mA. The transformer must be connected to the COMT 366 through the 1.3mm connector loc
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® CyberResearch Serial Communications COMT 366 Series Product Service Diagnosis and Debug CyberResearch, Inc. maintains technical support lines staffed by experienced Applications Engineers and Technicians. There is no charge to call and we will return your call promptly if it is received while our lines are busy. Most problems encountered with data acquisition products can be solved over the phone. Signal connections and programming are the two most common sources of difficulty. Cyb
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® COMT 366 Series CyberResearch Serial Communications Intentionally Blank 12 ©Copyright 2001 CyberResearch, Inc.
