DLM4100ET Extended Temperature Dial-up Modem

Data-Linc Group
DLM4100ET Extended Temperature Dial-up Modem

Installation and Operation Instructions

Chapter 1

Dial-up Modem

The DLM4100ET is a dial-up modem designed and manufactured to operate at the full industrial temperature range of -40C to +85C. It is DC powered with an operating voltage range of +9VDC to +15VDC. A 120VAC to +12VDC (unregulated) wall transformer type power supply is provided with the modem.

The DLM4100ET has been configured by the factory:

10-bit word:
-8 data bits, 1 stop bit, 1 start bit, no parity
-7 data bits, 1 stop bit, 1 start bit, even/odd parity
-7 data bits, 2 stop bits, 1 start bit, no parity.

Standard dialing commands are provided by the PC or PLC connected to the DLM4100ET.
As factory configured, the DLM4100ET will auto-answer on the first ring from any incoming call.

The DLM4100ET Dial-Up Modem has been pre-configured at the factory for typical PLC to PC use. It is intended for use as a remote/receiver in industrial applications under temperature conditions that would render a standard dial-up modem inoperative or unreliable. Since it has been pre-configured, in most cases the only command strings required are for dialing and hang-up. The command instructions to be entered in either a PC program or a PLC configuration program for dial-up operation are summarized in Appendix C.

The DLM4100ET is available as an enclosure mounted unit. When powered up, a red Power LED will be lit. The amber Carrier LED will be on when carrier communication has been established between modems. In place of a standard speaker, a piezo-element transducer has been utilized to provide reliable audio output throughout the entire temperature range of the modem.

The DLM4100ET has been specifically configured for industrial data communication between a PLC and a PC. The active RS-232 DB-9 pin connections are as follows (with respect to the RS-232 port on the modem):

   Pin Function
   1 Carrier Detect
   2 Transmit Data (Data from the modem to the PLC or PC.)
   3 Receive Data (Data into the modem from the PLC or PC.)
   5 Signal Ground

RTS, CTS, DSR and DTR are not active or connected on the DLM4100ET.

The DLM4100ET is not intended for the wide spectrum of applications usually associated with a full-featured dial-up/leased line modem. As a result, many options such as data compression, leased line operation, error correction, or external telephone jack are not available with the DLM4100ET. For a full-featured dial-up/leased line modem, consider a standard temperature range modem such as the Data-Linc DLM4000.


Unpacking the DLM4100ET
The complete modem package includes:

  1. The modem unit.
  2. This users manual.
  3. An RJ-11 phone cable.
  4. A power adapter.

Carefully inspect the package for shipping damage. If damage is found, immediately repack the modem in the original packing material and contact your dealer.

The LED Indicators

The LED indicators on the front panel of modem display the current modem operation and status as explained below:
O Green
Send Data (TXD)
Flashes when the modem is sending data to the remote modem or when receiving data from the local computer.
I Yellow
Receive Data (RXD)
Flashes when the modem is receiving data from the remote modem or when sending data to the local computer.
C Amber
Carrier Detect (CD)
On when remote modem carrier is detected.
P Red
On when there is power to the modem.

The power connector is a barrel jack, which accepts the barrel plug from the power adapter that comes with your modem.
Note: NEVER use an out-of-specification power adapter. It may damage your modem.
There is no power switch on the modem. It is turned on by connecting the barrel jack from the 120VAC-to-12VDC adapter to the power receptacle on the end of the modem. Always turn your computer on before turning on your modem, and turn your modem off before turning off your computer.

The DB-9F (female) connector on the end of the modem is to accept the RS-232 cable which connects the your computer or PLC to the modem. It utilizes standard RS-232C pin assignments and electronic standards.

There is one modular RJ-11 jack on the end of the modem. This is for the connection to the dial-up phone line.

The Serial Port and the RS-232 Cable:
Your computer or PLC must have an industry standard RS-232 serial port in order to use the DLM4100ET in RS-232 mode. If you do not have one, consult your dealer to acquire an RS-232 interface card for your computer.

You also need a serial cable between your modem and your PLC or computer (serial port). The correct cable for your modem has the following characteristics:

  1. DB-9M (male) connector at one end to match the modem connector.
  2. A connector that fits your computer’s serial port at the other end. For a PC user, the standard serial port card has a DB25M or DB9M connector so that your cable will have a DB25F or DB9F connector at the other end.
  3. The pin-to-pin connection of the cable will usually be “Straight Through.” Since your modem complies with industry standards in pin assignment, most standard modem cables should fit. However, you may refer to the appendices in this manual to check the pin assignment of the DLM4100ETconnector.

The Telephone Line Test and the Phone Cable
The quality of the telephone line significantly affects the reliability of data communications. Make sure that both the telephone system and telephone lines are in good order before the modem is connected. Before installing the modem, test the line condition by attaching a telephone handset. You should hear a clear dial tone. Then try placing a few calls. If the calls do not go through properly or the sound quality is not loud and clear, you probably have a poor quality telephone line. Contact your telephone service provider to have the problem cleared. It is preferable to connect your modem directly to an outside telephone line. If you connect to a private branch exchange (PBX) telephone system you may have to use a modified dial-out command string and to notify callers that must use modified call-in procedures.

Any good, operational, standard 4 -wire phone cable can be used to connect the incoming telephone line to the modem.

The Installation of the DLM4100
Your modem is a compact design small enough to fit in a small area, or can be mounted in any convenient location using the enclosure mounting holes. The distance between the computer and modem is determined by the length of the RS232C cable. However, an RS-232 cable should not be longer than 50ft, as signal distortion and interference may occur. A suitable location to place your modem shall be:

  1. Where you can easily reach a reliable AC power source, a wall outlet of good quality telephone line, and not too far from the computer.
  2. Where you can easily see the LED indicators, reach the power switch on the modem, and listen to the modem speaker.

Once you have chosen a proper location for your modem, follow the procedures below to connect the hardware:

  1. Make sure that both the modem and the computer are turned off.
  2. Connect the modem to the computer: Plug the DB-9M end of the RS-232 cable to the modem, and plug the other end of the cable to your computer’s serial port. Secure all of the screws on the connectors.
    Note: Verify and write down to which serial port (COM1 to COM4) your modem is connected to the computer, as the port number is required for communications software installation. Refer to the manual of your serial interface card or your terminal to find out how the port is configured.
  3. Connect the modem to the incoming telephone line: Use an appropriate cable to connect the incoming line to the RJ11 jack on the modem. Be sure that you have tested the line condition as described in the previous section.
  4. Supply power to the modem: Insert the cable-plug end of the power adapter into the power jack in the rear panel of the modem. Be sure to use only the adapter that comes with your modem.

The Communications Software
Since your modem follows the industrial standard in-modem command set, most of the popular on-the-shelf communications software packages will work with it.

Pay particular attention to the following parameter settings, as unsuccessful modem operation is often due to incorrect setting of:

  1. Serial port number – COM1 to COM4.
  2. Communications protocol – CCITT or Bell.
  3. Data format – number of data bits, parity and number of stop bits.
    (The DLM4100ET operates using 10 bit words ——– )

In order to communicate successfully, the protocol and data format of the two modems on-line must be set to 10-bit word as described previously. Otherwise, the connection may not be established or the data received may be unreadable (garbled).

Dialing String
Since the DLM4100ET comes from the factory pre-configured, an Initialization String should not be used so that the DLM4100ET pre-configuration is not changed. There are a limited number of dialing string prefixes that can be used with the DLM4100ET. Some of the primary Command Prefixes are:

Dial String ATDT
Escape Sequence    +++
Hang Up ATH0

Listed below are some examples which will illustrate the use of dialing prefix strings. (For the meaning of each command refer to the Command List in Appendix C).

ATS0=2 Instructs the modem to auto-answer an incoming call on the second ring.
ATS6=10DP Instructs the modem to wait for 10 seconds, then, use pulse dialing method to dial.
ATM2L3DT Turns on modem audio monitoring at all times with high volume.
ATB0DT Use CCITT protocol to establish connection with the remote modem and selects tone- dialing method.
AT&P1DP Pulse dials with the make/break ratio of 33/67 (in most European countries).
AT&P0DP Pulse dials with make/break ratio of 39/61 (in USA).

Chapter 2

Modem Operation
This chapter describes selected important DLM4100ET functions. It is designed to help you understand the function of your modem and how to use it.

Factory Default Profile
Your modem contains configuration profiles that are maintained even after the modem is turned off. These are permanently fixed at the factory.

Modes of Operation
The DLM4100ET has two operating modes; Data and Command. Modem setup is performed in Command mode. Communications occurs in Data mode.

Data Mode
The DLM4100ET enters Data mode after a link has been established and the “CONNECT” result code has been issued. In this mode, all signals are sent to the remote modem on the I pin (pin 2) of the DB-9 connector. Demodulated signals from the remote modem are received on the O pin (pin 3) of the DB-9 connector. The DLM4100ET exits from Data mode any time carrier is dropped or the escape sequence is received.

Command Mode
The DLM4100ET enters Command mode on power-up, reset, disconnect, or receipt of the escape sequence. Commands are input to the modem on I and result codes are issued on O. Data that is sent on the I line which does not conform to the command format is ignored.

Command Line Format
Modem commands must follow a specific format. Each command must begin with the “AT” prefix. The modem stores command lines in the command buffer. Command strings stored in the command buffer are executed upon receipt of a Carriage Return. Command strings can be edited while in the command buffer up until the command is executed.

The “AT” Prefix
Each command must be preceded by the “AT” prefix. The “A” and the “T” can both be upper or lower case, but not one upper and the other lower case. The prefix identifies the speed and parity of the host. The DLM4100ET measures the width of incoming bits to calculate speed and compares parity bits of the two characters (“A” and “T”) to determine parity.

The Command Line
A command line may include a string of commands. Commands are executed in the order they appear in the command string. A Carriage Return terminates the command string and triggers the DLM4100ET to execute the commands. Register S3 allows the user to select a character other than a Carriage Return to terminate the command string and execute the command. The command buffer holds up to 40 characters including the “AT” prefix. Spaces may be added for clarity to a command string without counting as characters. If the command buffer overflows, the modem issues an “ERROR” result code, and the commands are not executed.

A backspace can be used to edit the command string. Command strings can only be edited before they are executed. (See “Re-Execute Last Command, below).A backspace erases the previous character in the command line. Register S5 allows the user to select a character other than a backspace to edit the command string.

Re-Execute Last Command
The “A/” command causes the DLM4100ET to re-execute the command stored in the command buffer. A command string remains in the buffer until a new command is issued or power to the modem is turned off.

Omitted Parameters
Many commands require a parameter to specify the function, such as L being Speaker volume. A number, “n”, defines the operational status of “L”. For example, L3 would result in the speaker operating at it’s loudest setting. If no number is included in a command string, for those items requiring a number, the default is “0”.

The Escape Sequence
The escape sequence switches the modem from Data mode to Command mode while maintaining a communication link. The escape sequence uses an escape character, set by register S2, entered three times in succession. The default character is “+”. A guard timer before and after the sequence prevents normal data from triggering an escape.

Result Codes
The DLM4100ET issues a result code after each action. Result codes may be numeric codes, plain English statements, or disabled. Numeric result codes end with a Carriage Return, statements start and end with a Line Feed and a Carriage Return. Result codes are sent at the speed determined by the “AT” prefix.

To Appendix

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