LIMITED DISTANCE MODEM USER MANUAL by MICRO-AIDE CORP.
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LIMITED DISTANCE MODEM USER MANUAL A comprehensive document for the following LDM products: • LDM-1 standlalone • LDM-1 plug-in • LDM-16 nest Revised: June 16, 2009 MICRO-AIDE CORP. 626-915-5502 support@micro-aide.
Copyright © 2007 by MICRO-AIDE Corporation All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means without the written permission of MICRO-AIDE Corporation. The information in this document is subject to change without notice. MICRO-AIDE believes the information contained in this document to be accurate. However, MICRO-AIDE assumes no responsibility for any errors or omissions.
TABLE OF C ONTENTS CHAPTER 1 CHAPTER 2 CHAPTER 3 GENERAL DESCRIPTION Introduction . . . . . . . . Key Features . . . . . . . About This Manual . . . . Revision Level . . . . TxDOT Applications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LDM User Manual CHAPTER 4 APPENDIX A APPENDIX B Select Mode Pushbutton Switch . . . . . . . . . . Operating Modes . . . . . . . . . . . . . . . . . . . . Normal Mode . . . . . . . . . . . . . . . . . . . Test Mode A - Analog test with digital loop back . Test Mode B - Analog loop back with DTE data . Test Mode C - Analog loop back with test data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 . 20 .
C HAPTER 1 G ENERAL D ESCRIPTION INTRODUCTION MICRO-AIDE’s family of Limited Distance Modem (LDM) products can be used in a variety of data communications applications. The family consists of the following products. • LDM-1 standalone - a complete LDM (photographed on the cover page of this manual). • LDM-1 plug-in - functionally identical to the standalone version, it is a printed circuit board (PCB) that is mounted within the LDM-16 nest.
LDM User Manual The LDM-1 is easy to install and operate. Several self-test modes allow the user to verify its performance and network segment integrity. Light Emitting Diode (LED) indicators inform the user of all critical functions. KEY FEATURES Listed below are just a few of the features associated with MICRO-AIDE’s family of LDM products. • Broad transmission range, up to 25 miles, point-to-point, at 4800 Baud. • Data transparent transmission and asynchronous operation. • Baud rates from 75 to 19,200.
General Description - About This Manual MICRO-AIDE Corp. 685 Arrow Grand Circle, Covina, CA 91722 Tel: 626-915-5502 Fax: 626-331-9484 E-mail: support@micro-aide.com The MICRO-AIDE Material Return and Limited Warranty policies can be found on the inside back cover of this manual. REVISION LEVEL This User Manual makes specific reference to Revision D of the LDM-1. Additionally, this manual is applicable to LDM-1s that have been factory reworked to the Revision D level.
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C HAPTER 2 S ETUP AND I NSTALLATION INTRODUCTION This chapter describes how to properly unpack, set up and install each of the MICRO-AIDE LDM products. Typical point-to-point and multi-drop network installations are described. Figure 1 on page 6 includes an illustration of the front and rear panels of the LDM-1 standalone modem. The LDM-16 nest is illustrated in Figure 2 on page 7. NOTE: Unless otherwise stated, the term LDM-1 will refer to either version of the modem (i.e.
LDM User Manual Figure 1 - LDM-1 Standalone 6
Setup and Installation - Unpacking Figure 2 - LDM-16 Nest UNPACKING The LDM-1 standalone and LDM-16 nest are packed in individual containers that are properly sized for the unit. The LDM-1 plug-in PCBs are secured inside the LDM-16 nest. Abundant packing materials are provided to minimize mechanical shock to the contents. Before opening the shipping carton inspect the carton for damage. Damage to the container should be noted. Carefully remove the unit.
LDM User Manual LDM-1 BASICS The LDM-1 can be thought of as a device that extends the distance that RS-232 serial data can be transmitted and received. It does so over four-wire (i.e., two pair) private line networks. It includes a standard DB-25 female connector that allows for direct connection to any DTE device. The LDM-1 is configured as a DCE device. Refer to Figure 7 on page 31.
Setup and Installation - Network Types NETWORK TYPES The LDM-1 has several options and performance settings that can be configured by the user. Equalization, line termination and timer settings are among the various items. Before the LDM-1 can be properly set up the type of network that will be used must be understood and selected. The LDM-1 is designed for use in point-to-point and multi-drop networks. They are described in the following two sections.
LDM User Manual Figure 3 - Typical Point-to-Point Network MULTI-DROP NETWORK The multi-drop network involves two or more, two-pair cable segments. Each cable segment includes a Xmt and Rcv cable pair. The ends of the cable are connected to a single modem. These modems are also referred to as the nearand far-end modems. The master modem is located at the near end. The far end is equipped with a slave modem. The intersection of two cable segments forms a drop point.
Setup and Installation - Network Types • The RTS signal of the master modem can be permanently asserted. Refer to the section entitled “Permanently Asserting the RTS” on page 15. • RTS-CTS flow control must be used by each DTE device connected to a slave modem. • The near- to far-end cable length must not exceed the recommendations as listed in Table 5 on page 30 for the given cable size and selected Baud rate.
LDM User Manual ACCESSING THE LDM-1 PCB The various LDM-1 settings are controlled by jumpers and switches. They are located on the LDM-1’s PCB. Only the Equalization (SW3) setting can be accessed externally of the standalone modem. The other settings require that the cover of the standalone unit be removed or that the plug-in PCB be removed from its LDM-16 nest. The cover of the standalone unit can be removed by removing the four screws at the side of the unit.
Setup and Installation - Setup NOTE: The factory default switch and jumper settings for AX1 through AX5 and SW2 are satisfactory for use with a point-to-point network. The Equalization setting controlled by SW3 may need to be changed as required by the length of cable being used. Figure 5 illustrates the location of each setting on the LDM-1 PCB. Figure 5 - LDM-1 PCB SETUP In the sections that follow a description is provided for each jumper and switch setting.
LDM User Manual • If two modems are located at an end point in the network only one modem should be terminated. • Never terminate a modem located at a drop point. • There should never be more than two terminations per network channel. CAUTION: Failure to provide the correct termination and Equalization set- tings can result in significant communication errors. ENABLE XMT CHANNEL BUSY DETECTOR (AX3) The LDM-1 has a built-in carrier detector for its transmit channel.
Setup and Installation - Installation distinct settings are available. Table 2 details the correspondence between Equalization settings and switch positions. Equalization Setting Switch 3-1 Switch 3-2 Cable Length 1 (min. default) On On Short 2 Off On Mid-range 3 On Off Mid-range 4 (max.) Off Off Long On=down Off=up Table 2 - Equalization Settings Selecting the proper Equalization setting relates directly to cable length and wire diameter.
LDM User Manual mounting location. The standalone modem comes equipped with four vibration absorbing rubber feet. It is powered by a 24 Vac wall mount transformer (included with the LDM-1 standalone). Nearby access to 120 Vac power is required. The female connector of the transformer plugs directly into the round, male connector located at the rear panel of the modem. Refer to Figure 1 on page 6. The modem is always on when power is connected.
Setup and Installation - Installation any convenient location in the rack with four screws. Figure 2 on page 7 provides front and rear views of the LDM-16. The nest requires access to 120Vac power. It is equipped with a 2 Amp fuse located along the rear panel. ATTACHING THE NETWORK LINES The LDM-1 is designed to operate with four-wire private line networks. Both the transmit and receive channels are polarity sensitive.
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C HAPTER 3 O PERATION INTRODUCTION This chapter describes how to operate the LDM-1. An explanation of each LED indicator and use of the Select Mode pushbutton switch are also provided. Normal operation and the three test modes are described. INDICATORS AND CONTROLS LEDS The front panel of each LDM-1 includes a set of eight, multi-colored LED indicators. The location of each LED and the Select Mode pushbutton switch is depicted in Figure 1 on page 6.
LDM User Manual Label Name Color Description Pwr Power Red Modem has internal 5 Vdc power CD Carrier Detect Green Data is present on receive channel Flashes if Test Mode C is receiving data Tst2 & Tst1 Test 2 & Test 1 Red Off & Off: Normal Mode On & Off: Test Mode A Off & On: Test Mode B On & On: Test Mode C CTS Clear to Send Amber DTE can send data RTS Request to Send Amber DTE has asserted RTS Rcv Receive Data Red Receive channel is receiving data Xmt Transmit Data Red Transmi
Operation - Operating Modes Figure 6 - Test Mode Signal Flow NORMAL MODE Normal Mode is automatically selected when the LDM-1 is powered up. The modem will transmit/receive data to/from the network in accordance with the jumper and switch settings selected in the setup procedure. The RS-232 interface will be fully operational. The Tst2 and Tst1 LEDs are off when the modem is in Normal Mode.
LDM User Manual TEST MODE A - ANALOG TEST WITH DIGITAL LOOP BACK In Test Mode A the analog signal present at the receive channel is decoded into a digital data signal. The receive data signal is then presented to the modem’s transmitter section. The transmitter outputs the decoded data via the transmit channel. In Test Mode A the Tst2 and Tst1 LEDs will be on and off, respectively. The DTE interface is disabled in this test mode. The CD indicator will operate normally.
Operation - Operating Modes TEST MODE C - ANALOG LOOP BACK WITH TEST DATA Test Mode C also loops the transmit channel’s analog output signal to the input of the receive channel. However, the transmitted data is provided by an on-board test data generator. The test data consists of alternating mark and space bits. The test data has a Baud rate of 19,200. The receive and transmit channels are left terminated but are disconnected from the test data (i.e., test data is not sent to the network).
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C HAPTER 4 M AINTENANCE INTRODUCTION The primary purpose of this chapter is to describe the recommended troubleshooting method to be used with the LDM products. It should be referred to if ever a questionable symptom arises during the operation of any LDM device. The LDM products are designed to provide users with many years of troublefree operation. There are no user serviceable components in any LDM device. There are no consumable items or supplies that need to be replaced or replenished.
LDM User Manual PCB. PCB removal should be performed in accordance with the following procedure. Refer to Figure 2 on page 7. Power to the nest can be left on while PCBs are being removed and inserted. Damage will not occur provided normal care is exercised. CAUTION: Electrostatic discharges can cause serious damage to electronic components. Normal anti-static precautions are recommended when handling the LDM-1 PCB. • Disconnect the cables attached to the PCB at the rear of the nest.
Maintenance - Trouble-Shooting Guide nally. The identity and location of each jumper and switch is illustrated in Figure 5 on page 13. TROUBLE-SHOOTING GUIDE The following guide will assist the user in resolving problems that may occur with the operation of the LDM-1. It can be especially helpful when attempting to operate the modem for the first time. Procedures for resolving both local and remote problems are listed.
LDM User Manual Receive data contains errors Change Equalization settings to better match cable transmission properties Termination settings are incorrect (should measure 150 Ohm if On, 40KOhm if Off) Test Mode B does not echo sent charac- Set Equalization to setting 1 (minimum) ter U character is not issued in Test Mode C Set Equalization to setting 1 (minimum) Change Baud rate at DTE to 19,200 Table 4 - Trouble Shooting Guide (Continued) This completes the User Manual for the LDM-1.
A PPENDIX A TECHNICAL D ATA LDM-1 SPECIFICATIONS Physical Length: 8.6" Width: 5.3" Height: 1.9" Weight: 22 oz.
LDM User Manual Line Requirements Receiver Transmitter Dynamic Range Type: 4-wire Gauge: 19 to 24AWG Output Level -40 dBm to 0dBm Termination Impedance approximately 0dBm into 150 Ohm, .
Technical Data - Recommended Equalizations Settings RECOMMENDED EQUALIZATIONS SETTINGS The Equalization settings listed in Table 6 are for approximation purposes only. The optimum setting will vary from network to network. The transmission distances listed refer to the cable length measured from the near-end (master) modem to far-end (slave) modem.
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A PPENDIX B T X DOT A PPLICATIONS INTRODUCTION The LDM-1 is used in a variety of applications by the Texas Department of Transportation. It is frequently used in conjunction with the MICRO-AIDE Local Control Unit (LCU) and PSDM and ADU modules manufactured by Coastcom. Changeable message signs, vehicle detectors and camera pan-andtilt systems utilize the LDM-1 to facilitate RS-232 communications. NETWORK CONFIGURATIONS The LDM-1 can be used in point-to-point and multi-drop network configurations.
LDM User Manual ously active state. Refer to the section entitled “Permanently Asserting the RTS” on page 15 for details. MULTI-DROP Multi-drop networks require slave LDM-1s to be connected only to DTEs that support hardware handshaking. The MICRO-AIDE LCU supports this requirement. However, the hardware handshaking option must be enabled in the Coastcom PSDM. The user should consult Coastcom for information on how a PSDM is enabled for hardware handshaking.
TxDOT Applications - Test Software trolled by the Data Set Ready (DSR) signal which is always active. Crossing of the Receive Data and Transmit Data signals must also be performed. This cable is also useful when connecting an LDM-1 to any DTE that does not assert an RTS signal. However, its application is limited to point-to-point network segments. TEST SOFTWARE CTSCU.exe is a DOS application designed to test the operation of LCUs and LDM-1s. CTSCU.
LDM User Manual 1. The Rcv and Xmt Termination settings for the near-end (master) and farend (slave) modems must be set to On. The termination settings for all other modems must be set to Off. 2. Connect the PC’s serial comm. port to one end of the serial comm. cable. Connect the other end to the DTE port of the master LDM-1. 3. Connect the Xmt and Rcv + and - pins of each modem to the network cable. 4. Connect the DTE port of each slave modem to the RS-232 port of the LCU labeled “Communications”. 5.
TxDOT Applications - Test Software 2. Execute the Configure>Channel Configuration command. A screen similar to the following will be displayed. The Channel Number refers to the number of available comm. ports in the PC. Each of the LCU Numbers must correspond with one and only one LCU thumb wheel setting. In the example cited above, LCUs 1, 3 and 4 are included in the network to be tested. 3. Execute the Configure>Channel Communication Parameters command. Accept the default parameters as listed below.
LDM User Manual 4. Execute the Configure>LCU Communication Parameters command. Accept the default parameters as listed below. 5. Execute the Statistics>Reset Statistics File. Execute the Error>Reset Error/Log File command. 6. Execute the Control>Reset All LCUs command. After a brief delay a message will indicate that the reset was successful. 7. Execute the Control>Download LCU Code to All LCUs command. After a brief delay a message will indicate that the download was successful. 8.
TxDOT Applications - Test Software The test will run continuously until it is stopped by pressing the Esc key. The number of test blocks and errors by type will be reported. Run the test in accordance with the TxDOT acceptance criteria.
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Material Return Policy In the event the customer identifies a malfunction in any product, call or write MICRO-AIDE and obtain a Return Material Authorization (RMA) number from the customer service department.
MICRO-AIDE CORP. 685 Arrow Grand Circle Covina, CA 91722 Tel: 626-915-5502 Fax: 626-331-9484 E-mail: support@micro-aide.
