Tandy DCM212 User manual

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1200-Bps Intelligent Modem
DCM212
OPERATION MANUAL
cat. no. 26-1385

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Contents
Introduction 1
1Description of the DCM212 3
High and low speed operations 5
PROTOCOL (DIP) switches 6
Communications protocol 9
Manual v. automatic operation 10
Originate v. answer mode 10
2Tandy protocol mode operation 13
Sample programming sessions 13
Manual mode operations 17
Automatic mode operations 20
Analog self-test mode 24
ON-LINE mode abort 24
Result codes 27
3Hayes protocol mode operation 29
Command codes „29
Registers 33
Logons in MS-DOS operating systems 36
Result codes 38
Appendices
ATandy protocol reference 43
Wake-up command 43
Programming commands 44
BHayes protocol reference 59
Programming commands 59
Registers 67
Data line monitoring 73

Contents
CConnecting the DCM212 75
Telephone connections 75
Computer connections 77
Power source •*.. 78
DXENIX operations ." 79
£Optional modem configurations «81
Multi-line phone operation 81
RS-232C protocol extension 81
FTroubleshooting 83
Maintenance *83
Analog loop self-test 84
GSpecifications 85
Performance ........ 85
Electrical 86
Physical/environmental 87
HSchematic diagram 89
Index 91

Contents
List of Tables
Table 1. DIP Switch Settings in Tandy Protocol Mode .. 7
Table 2. DIP Switch Settings in Hayes Protocol Mode .. 9
Table 3. Result Codes (Tandy) 27
Table 4. Basic Command Codes (Hayes) 30
Table 5. Commands with Parameter (Hayes) 31
Table 6. Dialing and Answering Commands (Hayes) 32
Table 7. Registers (Hayes) 35
Table 8. Result Codes (Hayes) 39
Table 9. Programming Commands (Tandy) 44
Table 10. Valid Dialer Codes (Tandy) 44
Table 11. Dialer Codes (Hayes) 60
Table 12. Dialing Conditions in XCommand Mode
(Hayes) *62
Table 13. Advanced Dialing Subcommands (Hayes) 63
Table 14. Bit-mapped Register S13 (Hayes) 71
Table 15. Bit-mapped Register S14 (Hayes) 71
Table 16. Bit-mapped Register S15 (Hayes) 72
Table 17. Modem-to-Computer Cables 77
Table 18. Computer Option Boards 78
Table 19. Color Computer Software and Cables 78

Introduction
Tandy's DCM212 1200-bps Intelligent Modem has all the features need-
ed to enhance your data communications applications —including
adata output rate four times faster than that of a300 bits/second
modem.
This direct-connect, Bell 103/212A type modem is not only designed
with standard automatic dial, answer, and disconnect features, but also
with awide range of system configuration enhancements as well. Its
CPU provides operation in both Tandy and Hayes® protocol modes
—each selectable at the flip of aDIP switch. In the Hayes protocol
mode, your Modem is AT-compatible and capable of running with
Hayes software.
After dialing aphone number, the DCM 212 will monitor the call and
report its progress to your computer over the serial RS-232C link. You
can even control the dialing method —pulse or touch-tone —and
the number of times the phone should ring before being answered.
These functions and others are controlled by ASCII (American Stan-
dard Code for Information Interchange) encoded commands that you
program from your computer keyboard over the serial RS-232C inter-
face. Roughly equivalent to atelephone operator making acall, the
DCM 212's features include:
•Waiting as the phone rings until the dialed number is answered
•Hanging up and redialing later if the number is busy, or if the
call has not been answered after aspecified period of time
•Hanging up the handset at the end of acompleted call
One of the DCM 212's more advanced features is the ability to deter-
mine your computer's communications parameters (bit rate, data bits
per word, parity, and stop bits per word), and to adjust its own opera-
tion to meet system requirements using asimple command code
sequence.
Incorporating ahigh degree of intelligence, the DCM212 allows you
to operate your computer virtually unattended when linked to a
telephone, making possible awide range of telecommunications
applications. Used with the proper applications software package, the
Modem is capable of performing operations such as electronic mail
and shopping, central-data-base access, home banking and remote-
peripheral sharing.

Introduction
Another feature of the DCM212 is abuilt-in monitor speaker which
enables you to monitor audibly the dialing and data communication
progress. The situation is reported visually on your display with mes-
sages called results codes.
Sample programming sessions are provided in each section of this
manual to help familiarize you with the various functions of the
DCM 212 and to get you started using your Modem as quickly as
possible. After you have become familiar with the manual and your
Modem, the handy Quick Reference Card should keep you "up-and-
ninning!"

Description of the DCM212 1
When power is first applied, several indicators on the DCM 212's front
panel will illuminate —and remain lighted, depending on the status
of the computer's protocol and DIP switch settings. These 7indica-
tors show the Modem's internal and external operation status.
(D CD ®®® ® ®
o
iOFF
666666
POWER IHI-SPEED 'OFF HOOK ITERMINAL |CARRIER jTRANSMIT |RECEIVED
READY DETECT DATA DATA
ON TANDY
1200 BPS INTEUIGEHT HODEW DCM 21
2
T^T T5T
®
Figure 1, Front Control Panel
®Power switch turns the Modem ON or OFF. Be sure to turn it OFF
when the Modem is not being used.
©POWER indicator lights when power is on.
©HI-SPEED indicator lights when the Modem is in high speed (1200
bps) communications.
®OFF HOOK indicator lights when the Modem is ON LINE (con-
nected to the phone line).
®TERMINAL READY indicator lights when the terminal is sup-
plying DTR (Data Terminal Ready).
®CARRIER DETECT indicator lights when the Modem receives a
carrier tone or generates afalse carrier.
®TRANSMIT DATA indicator blinks when the Modem is transmit-
ting data.
®RECEIVED DATA indicator blinks when the Modem is receiving
data.

Description of the DCM212
RS-232C
ooooooo
oooooooooooooljf^i >OOOOQJl ^
PROTOCOL PHONE
ayaHdHbu
POWER .
WALL
JACK \
D
-^
®©©e
Figure 2. Rear Panel
®RS-232C standard DB-2S jack connects the Modem to the RS-232C
interface of your computer.
©PROTOCOL (DIP) switches control the Modem's power-up con-
dition (refer to PROTOCOL (DIP) switches later in this section).
(§) PHONE jack connects the telephone to the Modem.
®POWER jack connects the Modem to the AC power adapter.
(5) WALL JACK phone line cord connects the Modem to the telephone
line.
Before you connect the DCM212, first read the instructions in Ap-
pendix C, Connecting the DCM212. Be sure to turn OFF power to
the Modem and to the computer!

Chapter 1
Typical connection
Figure 3. ATypical Connection
High and low speed operations
The DCM212 Modem automatically synchronizes with standard speed
rates of 300 and 1200 bits per second (bps).
Switching from high speed (1200 bps) to low speed (300 bps) opera-
tion occurs when the DCM212 receives either the wake-up code in the
Tandy protocol mode, or the attention code in Hayes protocol mode.
When the Modem detects 1200 bps after receiving the code sequence,
it will communicate in high speed. If it is awakened at 300 bps, low
speed operation will be used.
The originating station always determines the speed of operation. If
you wake up the DCM 212 in low speed mode intending to call ahigh
speed modem, the DCM212 will select 300-bps operation none the less
if that modem has low-speed detection circuitry. Otherwise, the
DCM212 must be set to high speed before calling aremote modem.

Description of the DCM212
PROTOCOL (DIP) switches
DIP switches control the DCM212's power-up condition. These
switches must be set before you turn the power ON.
First, you will have to decide whether you want to use the Modem in
the Tandy protocol mode or Hayes protocol mode. If you are using
Tandy communications software, you will want to set it for Tandy
protocol. For use with Hayes communications software, set it to the
Hayes protocol mode, (Both the Tandy 1000 and 1200 personal com-
puters can be used with either communications software.)
Tandy Protocol
When you select Tandy protocol mode, set Switch 2to OFF. Figure
4shows an example of the suggested switch positions.
NO FUNCTION
TRUE CARRIER —
TANDY PROTOCOL
NO FUNCTION
NO FUNCTION J
HAYES PROTOCOL
FORCED CARRIER —
'
NO FUNCTION
NO FUNCTION
I— AUTO ANSWER DISABLE
NO FUNCTION
TRUE DTR
FORCED DTR
NO FUNCTION
1—AUTO ANSWER ENABLE
NO FUNCTION
Figure 4. DIP Switch Settings in Tandy Protocol Mode

Chapter 1
Notes:
1. When Switch 3is ON, the Gcommand (software control
for FCD) is disabled and the FCD (Forced Carrier Detect)
signal is issued to the terminal as long as the Modem is ON.
When the switch is OFF, the FCD signal can be software-
controlled by the Gcommand and the parameter FORCE
CARDET^ shows the FCD signal condition. The CD indi-
cator reflects true carrier status when the FCD signal is OFF.
2. When Switch 6is ON, the Modem assumes auto-answer
mode with 1200 bps. Be sure to set your Computer to 1200
bps before turning the Modem on.
Table 1. DIP Switch Settings in Tandy Protocol Mode
SW Position Function
1Should be OFF
2Should be OFF
3ON
OFF
No function
Set the Modem to Tandy protocol mode.
Forced carrier detect. Modem issues an FCD sig-
nal to computer upon power-up.
True carrier detect. FCD signal can be turned on
and off with the Gcommand, under software
control.
4Should be OFF No function
5Should be OFF No function
6ON Auto-answer mode enabled
OFF Auto-answer mode disabled
7Should be OFF No function
8ON Forced DTR. Modem acceoi
OFF
computer any time without aDTR (Data Terminal
Ready) signal.
True DTR. Modem is OFF until it receives atrue
DTR signal from the computer.

Description of the DCM212
Hayes Protocol
When you want to use your DCM212 in Hayes protocol mode, posi-
tion Switch 2to ON. In this protocol mode, the other switches func-
tion differently from those in Tandy protocol. Figure 5shows which
switch settings can be used for easy operation.
COMMAND ECHO OFF
TRUE CARRIER —
i
TANDY PROTOCOL
AUTO ANSWER DISABLE n
I—NUMERIC RESULT CODES
|— ENABLE COMMAND RECOGNITION
SEND RESULT CODES
TRUE DTR
[~r
iH ykyHHB
01
N2345G78
:Jj
AUTO ANSWER ENABLE
HAYES PROTOCOL
FORCED CARRIER —
COMMAND ECHO ON
LLFORCED DTR
NO RESULT CODES
'—DISABLE COMMAND RECOGNITION
1—VERBAL RESULT CODES
Figure 5. DIP Switch Settings in Hayes Protocol Mode
Note: When Switch 1is ON, the Modem assumes auto answer
in 1200-bps operation.
8

Chapter I
Table 2. DIP Switch Se *iigs in Hayes Protocol Mode
sw Position Function
1ON Auto-answer mode ON
OFF Auto-answer mode OFF
2Should be ON Sets the Modem to Hayes protocol mode.
3ON Forced carrier detect
OFF True carrier detect
4ON Command echo ON (echoes command characters
to verify that the Modem accurately receives the
commands sent to it).
OFF Command echo OFF
5ON Displays verbal result codes.
OFF Displays numerical result codes.
6ON Disables command recognition. Modem does not
recognize commands.
OFF Enables command recognition. Modem recognizes
commands.
7ON Result codes disabled (disables Switch 5)
OFF Result codes enabled (enables Switch 5)
8ON Forced data terminal ready signal
OFF True data terminal ready signal
Communications protocol
The following criteria must be met before computer-to-computer com-
munication can occur.
1. Both computers must have the same communications protocol:
Operation speed (300 bps or 1200 bps)
Word length (7 bits or 8bits)
Parity (even, odd or none)
Number of stop bits (1 or 2 bits)
See your computer owner's manual for instructions on setting the
communications protocol.
9

Description of the DCM212
When opened for programming by the wake up or attention code se-
quence, the DCM212 will automatically synchronize the speed rate,
word length, parity, and stop-bit numbers (communications protocol)
of your computer system.
2. One modem must be in originate mode and the other must be in
answer mode. Usually, when you call another computer, you
should be in originate mode. When you receive acall, you should
be in answer mode.
Manual v. automatic operation
When you want to dial an information service (such as CompuServe
or Dow Jones) or communicate with another person whose computer
is also using VIDTEX, set the Modem to manual operation mode. In
this mode, you can control what the system does by manually dialing
and answering the phone.
When you want the DCM212 to dial aphone number or answer the
phone for you, set it to automatic operation mode. In this mode, the
Modem dials the phone number you store in its memory or answers
the phone when someone calls you. Automatic mode, for instance, lets
you dial the information service number without picking up the phone
—just type the number along with the proper DCM212 programming
commands on the computer keyboard.
Originate v. answer mode
To place acall to an information service or another person using
VIDTEX, set the DCM 212 to originate mode. In this mode, the call
originates from your computer. When you want to receive acall (an-
swer the phone), set the DCM 212 to answer mode. Note that originate
and answer modes can be used either manually or automatically.
10

Chapter 1
Helpful Tip:
When you use your DCM212 for the first time or when you seem to
be getting garbled data, use the self-test mode to help you find the
cause of the problem. Refer to the section on "self-test" in Appendix
A, Tandy protocol reference, or in Appendix B, Hayes protocol
reference.
If you plan to use the DCM212 in Tandy protocol mode only, you may
skip Chapter 3and Appendix B. However, if you intend to use it in
Hayes protocol mode only, you may disregard Chapter 2and appendices
Aand D. Refer also to the operation manual which accompanies your
communications software package.
11

Tandy protocol mode operation 2
This chapter will give you an idea of what the DCM212 can do in the
Tandy protocol mode. The Videotex Plus communications package for
Tandy's Model II, 12, 16 and 6000 microcomputers is used in the sam-
ple sessions following. With this package you can communicate with
avariety of information services and host computer systems. The ex-
amples will help familiarize you with some of the operations the Modem
is capable of performing.
If you are using an MS-DOS operating system, feel free to move to
the auto logon session using DeskMate's Telecom in Chapter 3, Hayes
protocol mode operation. XENIX® users may want to skip to
Appendix D.
For adetailed discussion of all the available commands in Tandy pro-
tocol, refer to Appendix A,
Sample programming sessions
All Modem functions are controlled by ASCII encoded commands that
you send from your computer keyboard. Use the wake-up com-
mand QQto open the DCM212 for programming.
When this 2-key code sequence is issued, the DCM212 automatically
adapts the communications protocol (speed, word length, parity, and
stop bits) of your computer.
1. Check again that all peripherals are correctly connected and receiv-
ing power.
2. Set the DIP switches as follows:
,m ill mmmmmm
12345 6 78
N
3. Flip the power switch on the Modem's front panel to the ON po-
sition.
4. Load and run the Videotex Plus communications program as
described in your user's guide,
5. At TRSDOS Ready, type VIDTEX (ENTER) .TERMINAL
READY indicator lights.
13

Tandy protocol mode operation
6. Set the communications protocol (bit speed, word size, parity, and
stop bits) that you want to use.
7. Open the DCM 212 Modem for programming by typing the wake-
up command sequence. Press QQ.
You may have noticed that the *did not echo until you pressed Q.
That's because both keys are needed to determine the bit speed rate.
When the correct operation speed is detected, the character *(HEX
*2A') is output.
The Modem is now in the command receptive state and is waiting for
you to begin programming or setting the internal switches that will
tell it what operations are to be performed.
8. When the *echoes on your computer screen, press (T) for the LIST
command to display or list the Modem's current parameters. When
cold-started, the list shows:
PHONE NO
10 BITS/CHAR
ABORT CHAR
LOSS OF CARR
SEND SPACE
RECEIVE SPACE
ABORT ENABLE
HIGH SPEED
ANALOG LOOP
ORIG MODE
MANUAL MODE
FORCE CAROET
PULSE DIAL
SLOW DIAL
Y
14H
Y
N
Y
Y
Y
N
Y
N
Y
Y
Y
After the parameters are listed, the Modem returns to the command
receptive state where it waits for further instructions.
Note: The above list appears when you select high speed mode
at step 6. If you select low speed mode, the 2nd line (10
BITS/CHAR:Y) is not displayed and 8th line changes to HIGH
SPEED:N.
14