The DSC Downloading Software (DLS) DOS version 6.5x supports only a short list of modem types.  There has been success using some other modems, not listed in the DLS manual as supported modems.  This document describes some tests done on a Hayes compatible 1200-baud modem, Hayes 2400-baud modem, and a SmarTEAM 2400AT modem, and the successful integration of these modem with the DLS software.
 

DISCUSSION

The modem problem is twofold:

• The DLS software does not have options for the user to easily modify the modem initialization string (commands), and
• the modem must be capable of operating at 110 baud and be able to change baud rates 'on the fly'.

The first problem can be tackled by modifying the MODEMSTR.FIL file.  Information on doing this is included in this document.

The baud rate requirement can only be addressed by the selection of an appropriate modem.  The requirement to operate at 110 baud is limiting.  The DLS software uses 1200 baud (or 110 baud) for initialization and dialling and then change to either 300 baud or 110 baud (Bell 103) for communication to the panel.

I have found that not all modems will easily and reliability change baud rates on the fly.  For example, the Hayes Smartmodem 1200 tested would not reliability change baud rate in the manner required by the DLS software, but most of the time it worked fine.

Considerable effort was put into trying to make USRobotics compatible with the DSC software, without success.

MODEM INITIALIZATION

The problem with initialization strings is that if there is an error, any error, or a unsupported command, anywhere in the string, the modem (usually) ignores the whole string.  A solution, used here, is to place some commands on separate strings, each to be sent to the modem individually.  If the modem not understand one of the strings, the others, with recognized commands, are accepted and stored.  This approach has been used to create a ‘somewhat’ universal set of initialization commands that will work with more than one modem.  This universal approach is discussed later in this document.

These commands are stored in a file called the MODEMSTR.FIL file.

MODIFICATIONS to the MODEMSTR.FIL file:
Additional commands can also be sent to the modem.  Additional commands are added by modifying the MODEM COMMAND SECTION in the MODEMSTR.FIL file (located in the DSC sub directory on the computer hard drive).  These additional commands if added, are sent after the default commands described above are sent.  See Appendix E of the Downloading Software manual, Modem Command File.

Each command line (string) must start with the standard 'AT' characters.

MODIFICATIONS to the MODEMSTR.FIL file for use with a SmarTEAM 2400AT Modem

Add these lines to the MODEMSTR.FIL file MODEM COMMAND SECTION then a SmarTEAM 2400AT modem will work:

ATH0
ATL1
ATS7=250S10=250S9=1Q0V0E0X4&D2&C0
ATH0
 

The complete MODEMSTR.FIL would be:

DIALING PREFIX: DT
MODEM COMMAND SECTION
ATH0
ATL1
ATS7=250S10=250S9=1Q0V0E0X4&D2&C0
ATH0
END OF FILE
 

Note:  The "F1" and "C1" commands are not included in this command string as they are not supported by the SmarTEAM 2400AT modem.

Note: The &D2 enables the ‘Modem follows DTR’ function.  The modem goes into command mode when the computer drops the DTR line.  The &C0 command forces the CD (Carrier Detect) modem line to be always ON.

Also, this modem must have dip switches set for ‘CD Carrier Detect line always ON’ and ‘Modem follows DTR’.

In the Program Configuration menu, the modem is set to 'Compatible 2400 Baud Modem mode'.  The modem will echo ‘ERROR’ and ignore the default initialization string sent by the DLS software.  This will not cause a problem as the string in MODEMSTR.FIL will correctly configure the modem.

The above is an example, the modem MODEMSTR.FIL is written for only one type of modem.  I recommend that a more universal command set be used.  This command set will work with more types of modems.  See the next section.

A MORE ‘UNIVERSAL’ APPROACH TO MODEM COMMANDS

This is a ‘somewhat’ universal command set.  It has been designed to work with these 3 modems, and requires no changes when switching between them.  It should work with many others.

The approach has been to place commands which are not ‘universally supported’ on separate lines in the command section.  When a modem which does not ‘support’ the individual command receives it, it will simply echo ERROR and ignore it.  For example, most 1200-baud modems do not support ‘&’ commands, so by placing them on separate line or lines in the command section they will not cause any ‘harm’ to the recognized commands on other lines.  If they were to be placed within a long command string, then the entire command string, including ‘supported’ commands would be ignored, and the modem would fail to work.

The recommended MODEMSTR.FIL file is:

DIALING PREFIX: DT
MODEM COMMAND SECTION
ATZ
ATL1
AT&D2&C0
ATX4
ATS7=250S10=250S9=1Q0V0E0
END OF FILE

The MODEMSTR.FIL file is located in the DSC sub directory on the computer hard drive.

The ATZ command initializes the modem to the reset state, removing the effects of the software initialization string.  The ‘AT&_’ commands are ignored by 1200-baud modems but are recognized by the HAYES 2400 baud modems.

The functions of the other commands is as follows:
L1        (Speaker)
ATX4   (Enable result codes)
&D2     (Modem follows DTR, goes into command mode when DTR dropped)
&C0     (CD Carrier Detect line always ON)

These modems must have their dip switches set for CD Carrier Detect line always ON and Modem follows DTR.

In the Program Configuration menu select 'Compatible 1200 Baud Modem'.

See the next sections on other required DLS software settings.

PROGRAM CONFIGURATION MENU SETTINGS

MODEM
Although the SmarTEAM 2400AT modem is a 2400-baud modem, less than full success was achieved by using the 'Compatible 2400 Baud Modem' setting.  The additional commands in the modem command string add no value as the string causes an error and is ignored, but they seem to cause unexplained problems for the software when changing between downloading menu functions while connected to the panel (the customer's alarm panel).  The software complains that the modem is not present.  The 1200-baud modem setting seems to work better.  In the Program Configuration menu select 'Compatible 1200 Baud Modem'.

MODEM INITIALIZATION SPEED
In the Program Configuration menu, two Initialization Speed choices are available, 'Slow' and 'Fast'.  The 'slow' setting initializes the modem at 110 baud.  The 'fast' setting initializes the modem at 1200 baud.  Both seem to work fine, with the 'Fast' being much faster.  'Fast' is recommended.  In any case the communication to the panels appears to be done at 110 baud, or 1200, baud depending on the panel.

SUMMARY

SOFTWARE:
The DSC Downloading software used in these tests was DLS-1 version V6.5C.
 
 

Tests were done on the DLS software to determine what commands were being sent to the modem for different software modem settings.  The serial line to the modem was monitored using a separate terminal and the following command strings were recorded.

===================================
In the 'Compatible 1200 Baud Modem' and 'Practical Peripherals PM1200' modes the DLS software sends the following command string to the modem:

ATS7=250S10=250S9=1F1Q0C1V0E0L1M1X4

Each command is shown here for clarity:
S7=250   (Wait for carrier in sec)
S10=250  (Disconnect 1/10 sec)
S9=1     (CD Detect response time 1/10 sec)
F1       (NOT recognized by compatible Hayes Smartmodem 2400 B)
Q0
C1       (NOT recognized by compatible Hayes Smartmodem 2400 B)
V0       (Numeric result codes, 0 for OK)
E0       (Echo disabled)
L1       (Speaker)
M1       (Speaker)
X4       (Result codes)
 

===================================
In 'Compatible 2400 Baud Modem mode' the DLS software sends the following command string to the modem:
ATS7=250S10=250S9=1F1Q0C1V0E0L1M1X4&D2&C0

Each command is shown here for clarity:
S7=250
S10=250
S9=1
F1       (NOT recognized by compatible Hayes Smartmodem 2400 B)
Q0
C1       (NOT recognized by compatible Hayes Smartmodem 2400 B)
V0
E0
L1
M1
X4
&D2     (Modem follows DTR, goes into command mode when DTR dropped)
&C0     (CD Carrier Detect line always ON)
 

===================================
In the 'HAYES Smartmodem Optima 2400' mode the DLS software sends the following command string to the modem:

ATS7=250S10=250S9=1F1Q0C1V0E0L1M1X4&D2&C0&K0&Q0B16N0

Each command is shown here for clarity:
S7=250
S10=250
S9=1
F1
Q0
C1
V0
E0
L1
M1
X4
&D2     (Modem follows DTR, goes into command mode when DTR dropped)
&C0     (CD Carrier Detect line always ON)
&K0     (No flow control)
&Q0     (No error control)
B16     (Bell 103 at 300 baud)
N0      (No fallback)

===================================
In the 'STRADCOM” modem mode the DLS software sends the following command string to the modem:

ATS7=250S10=250S9=1F1Q0C1V0E0L1M1X4B1

Each command is shown here for clarity:
S7=250
S10=250
S9=1
F1
Q0
C1
V0
E0
L1
M1
X4
B1 ( ?)
 
 

The MODEMSTR.FIL file is located in the DSC sub directory on the computer hard drive.  The default MODEMSTR.FIL file is:

DIALING PREFIX: DT
MODEM COMMAND SECTION
END OF FILE
 
 

This modem was successfully used with Power 832 panels that communicate at 300 baud, but will not work with slower panels, for example PC1550, which communicate only at the very slow 110 baud.

Test MODEMSTR.FIL file for Hayes ACCURA 288 V.36 +FAX modem:

DIALING PREFIX: DT
MODEM COMMAND SECTION
ATZ
AT&D2
AT&C0
AT&K0
AT&Q0
ATL3
ATX4
ATS7=250S10=250S9=1Q0V0E0
END OF FILE

Special commands do the following:
&D2     (Modem follows DTR, goes into command mode when DTR dropped)
&C0     (CD Carrier Detect line always ON)
&K0     (No flow control)
&Q0     (No error control)
 
 

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Dec 6, 1998
Updated Dec 11, 1998
Dec 20, 1998
August 13, 2000