GDI SM2400 User manual

MODEL SM2400
2400 BAUD
DIAL-UP MODEM
SMART MODEM
USER GUIDE
280 Interstate 80 West Exit 1 / PO Box 1330, Verdi NV 89439
Phone: [phone] Fax: [phone] E-mail: [email protected]

PROPRIETARY DATA
This document contains confidential, proprietary data with all rights
and titles reserved by GDI Communications LLC. By accepting
this document, the recipient assumes custody hereof and agrees not
to disclose this data or any portion of this data to any unauthorized
person without the prior written consent of GDI Communications
LLC. Recipient further agrees not to incorporate these drawings,
specifications or technical information, in whole or in part, in any
other product or endeavor.
THIS LEGEND SHALL BE INCLUDED ON
ANY REPRODUCTION OF THIS DOCUMENT

GDI Communications LLC
MODEL SM2400
Smart Modem
Revision B-2.0
USERS MANUAL
GENERAL
The GDI Model SM2400 is a Hayes compatible Dial-up modem, designed for plug-in
compatibility with 170 series Traffic Controllers. It is intended to allow, with proper
software support, communication between a 170 and a host computer over standard dial-
up or leased telephone lines. The GDI Model SM2400 includes a modulator, demodulator,
filters, phone line interface, and 170 controller interface. It offers 300/1200/2400 baud
transmission & reception, auto-dial/-answer/-speed detect, and Hayes command set
compatibility, all on a single board with the standard Model 400 form factor.
In addition to all of the features normally found in a Hayes-compatible modem, the GDI
Model SM2400 is fully temperature tested.
FEATURES
- Form factor consistent with the standard Model 400.
- Front edge mounted status indicators.
- Industry standard 'AT' command set.
- Auto-Dial Auto-Answer Auto-speed detect.
- Highly flexible configuration options.
- Fully temperature tested.
- Configuration options stored in NVRAM - no jumpers.
- Call progress monitor speaker.
- May be cable connected to auxiliary ACIA

TABLE OF CONTENTS PAGE
GENERAL CHARACTERISTICS …………………………………………………3
INSTALLATION ……………………………………………………………………6
SHIPPING CONFIGURATION…………………………………………………… 7
ADJUSTMENTS…………………………………………………………………… 7
THEORY OF OPERATION ……………………………………………………… 8
System Description ………………………………………………………… 8
Description of Circuit Operation…………………………………………… 9
MAINTENANCE………………………………………………………………… 10
Preventive Maintenance…………………………………………………... 10
Alignments………………………………………………………………… 10
Trouble Analysis…………………………………………………………... 10
Special Considerations…………………………………………………….. 10
Waveforms and Voltage Measurements……………………………………10
TEST PROCEDURE……………………………………………………………….11
COMMAND SET…………………………………………………………………. 12
CONFIGURATION (S) REGISTERS……………………………………………. 24
PROGRAMMABLE OPTIONS NOT SAVED IN NVRAM……………………. 30
PROGRAMMABLE OPTIONS SAVED IN NVRAM………………………….. 30
COMMAND SUMMARY………………………………………………………... 31

General Characteristics
INDICATORS TXD Transmitted Data
RXD Received Data
OH Off Hook, on when modem is off hook
DTR Terminal Ready, on when host is ready
HS High Speed, on when in 2400 baud mode
DCD Carrier Detected
AA Originate/Answer mode, on when in answer mode
OPERATING TEMPERATURE RANGE
-30°C to +70°C
HUMIDITY
95% Relative Humidity, non-condensing
LINE REQUIREMENTS
(a) Public switched telephone network
(b) Private unconditioned leased lines
MODES OF OPERATION
Asynchronous
Full or half duplex
Automatic and manual call originate Automatic and manual call answer
COMPATIBILITY
CCITT V.22 bis, V.22 A&B, V.21, Bell 212A and Bell 103 Automatically adapts to
calling or called modem
ASYNCHRONOUS DATA RATES
2400 and 1200 bps, character asynchronous 0 - 300 bps asynchronous
ASYNCHRONOUS CHARACTER FORMAT
Character length of 8, 9, 10 or 11 bits Parity - odd, even, mark, space or none
ASYNCHRONOUS OVERSPEED/UNDERSPEED RANGE
Nominal rate -2.5% to +1.25% in character asynchronous mode Data formatter follows
CCITT V.22 bis and Bell 212A
TELEPHONE LINE INTERFACE
Meets FCC part 68 requirements
Maximum transmit level -9dBm (600 fl) Two wire full duplex. Uses TIP and RING
MODULATION
V.22 bis - 16 Level Quadrature Amplitude Modulation (QAM)
V.22 and 212A - 4 Level Differential Phase Shift Keying (DPSK)
V.21 and 103 - Phase-Coherent Frequecy Shift Keying (FSK)

TRANSMIT CARRIER FREQUENCIES
V.22 bis:
V.22:
212A: ORIGINATE 1200 Hz +/- 0.01%
ANSWER 2400 Hz +/- 0.01%
V.21 @ 300 bps:
ORIGINATE ‘ space’ 1180 Hz +/- 0.01%
ORIGINATE ‘ mark’ 980 Hz +/- 0.01%
ANSWER ‘ space’ 1850 Hz +/- 0.01%
ANSWER ‘ mark’ 1650 Hz +/- 0.01%
Bell 103:
ORIGINATE ‘ space’ 1070 Hz +/- 0.01%
ORIGINATE ‘ mark’ 1270 Hz +/- 0.01%
ANSWER ‘ space’ 2020 Hz +/- 0.01%
ANSWER ‘ mark’ 2225 Hz +/- 0.01%
LINE EQUALIZATION
(a) Fixed compromise equalization in transmitter
(b) Adaptive equalizer for 1200 and 2400 bps in receiver
INTERFACE SIGNALS
RS232C levels with CCITT V.24 protocols
AUTODIALER TYPE
DTMF or pulse type dialing, specified in commands
DTMF TONE PAIR BALANCE
Better than 3dB
DTMF TONE DURATION AND SPACING
Variable from 50 to 255 milliseconds (Register S11)
Default duration 100 milliseconds
PULSE DIALING RATE
10 pulses per second
PULSE DIALING DUTY CYCLE
39/61% (US) or 33/67% (UK Hong Kong) make/break ratio
PULSE DIALING INTERDIGIT INTERVAL
650 milliseconds
BILLING DELAY INTERVAL
2 seconds silent time, before answer tone

GUARD TONES
Guard tones of 1800 Hz or 550 Hz may is transmitted by the answering modem, for echo
suppression. Default - no guard tone. Guard tone will not be transmitted in Bell 212A or
103 modes.
COMMAND BUFFER SIZE
40 Characters maximum, which includes the required carriage return. The modem does
not count the required AT prefix.
FAILED CALL TIMER
2-255 seconds (Defaults to 30 seconds)
RESULT CODES (TO TERMINAL OR 170)
Ability to limit, abbreviate, or suppress codes
RECEIVE CARRIER DETECT
Off-to-On Threshold: -43 dBm On-to-Off Threshold: -48 dBm
Hysteresis: Greater than 2 dB
TIMING
Request to send-Clear to send Delay
As per CCITT and BELL protocols during modem handshaking.
Delay specified by register S26. (default 10 mS)
TIMING
DCD ON delay
As per CCITT and BELL protocols (600 mS)
TIMING
DCD OFF delay
52.5 +/- 12.5 mS at 2400,1200 bps
17 +/- 7 mS at 300 bps
PERFORMANCE
Bit Error Rate of 1 bit per 100,000 for a S/Noise Ratio of 10dB
TxD Level -10 dBm
RxD Level -45 dBm
POWER
+12 Volts +/- 5% at 200 mA
-12 Volts +/- 5% at 200 mA
170 CONTROLLER INTERFACE
ETA RS-232-C via standard 400 modem edge connector pinout or a 9 pin Male D-Sub
connector J14, user selectable.

J14 PINOUT (9 PIN MALE RS232)
Pin Function Direction
1 DCD (Data Carrier Detected) Output
2 RXD (Received Data) Output
3 TXD (Transmitted Data) Input
4 DTR (Data Terminal Ready) Input
5 GND (Signal Ground) Common
6 DSR (Data Set Ready) Output
7 RTS (Request To Send) Input
8 CTS (Clear To Send) Output
170 EDGE CONNECTOR PINOUT
Pin Function
A & B Signal Common (DC Ground)
C & D +12 Volts
E & F -12 Volts
K DCD (Data Carrier Detected)
L RTS (Request To Send)
M TXD (Transmitted Data)
N CTS (Clear To Send)
P RXD (Received Data)
TELCO CONNECTOR PINOUT (LINE)
Pin Function Direction
4 TIP TERMINAL To/From RJ11C jack
3 RING TERMINAL To/From RJ11C jack
INSTALLATION
Before installing the Model SM2400, it is necessary to determine if the controller
application software expects to talk to the Smart Modem via ACIA1 (modem slot and C2)
or ACIA2 (C20 only). If the software communicates with the smart modem via ACIA1,
installation consists of simply plugging the modem into the modem slot and connecting
the phone line to the modular jack (LINE). If the softwar talks to the Smart Modem
through ACIA2 (C20), it is necessary to remove the jumper arrangement plugged into J3
(Edge Connector Enable) and supply a cable between C20 and the 9 pin connector of the
modem (J14). One can then plug in the modem and connect the phone line.
If you have completed the steps in the above paragraph and are still experiencing
problems you are encouraged to contact your software supplier and/or GDI. The Model
SM2400 is shipped from the factory in the most commonly used operating configuration
but some software suppliers require different operating options that can be accommodated
by reconfiguring non-volatile RAM.

ADJUSTMENTS
NVRAM
The Model SM2400 is equipped with Non Volatile Random Access Memory. This
memory stores modem operating parameters even when power is off. Two complete User
Profiles and four Dialing Strings may be stored. This eliminates the need for jumper
arrangements while allowing more flexibility. A detailed description of which parameters
are stored in this memory and how to alter its contents is given in the Command Set
section.
Switches
The GDI Model SM2400 has an eight position DIP switch (SW1) that is used to 'strap'
operating parameters. Only positions 1 through 6 are used. The following is a description
of their function.
Switches 1 through 4 - TXn
These switch positions are used to adjust transmit levels. They are preset at the factory
and should NOT be change
user as doing so may cause a violation of FCC regulations and/or compromise
performance. If these switches are inadvertently altered, restore them to: switch 1 ON,
Switches 2,3,4 OFF
Switch 5 - BELL/CCITT
This switch position has been superseded by an enhanced "B" command. It should be left
in the "OFF" condition.
Switch 6 - Dumb/Smart
If switch 6 is OFF the modem will ignore commands and refrain from sending result
codes to the terminal (Dumb mode). To use the dumb mode, first store operating
parameters in NVRAM, then turn switch 6 OFF. At the next power up the modem will
assume the dumb mode. Turn switch 6 ON and power up to reestablish Smart mode.
(factory default ON)
SHIPPING CONFIGURATION
The modem is shipped from GDI in a slightly different configuration than described in the
command &F. This is for compatibility with most 'traffic' software. The differences are:
1200 baud instead of 2400 baud communication rate, and Auto-Answer enabled.
To restore the modem to shipping configuration:
1. Connect to 1200 baud terminal, power off, back on.
2. AT&F <return> fetch factory profile
3. AT&C0&D1 <return> DCD and DTR options
3. ATS0=1 <return> Auto-Answer enabled (first ring)
4. AT&W0 <return> Write current profile to NVRAM

THEORY OF OPERATION
System Description
The Model SM2400 modem is designed to provide the Traffic Industry with the
advantages of a Hayes compatible Dial-up modem, while minimizing limitations imposed
by connecting it to a 170's 6850 Asynchronous Communications Interface Adapter
(ACIA). The 6850 RS-232-C control lines are not sufficient in number to provide
complete control over an off-the-shelf Hayes modem. The 170 communication signal
lines, available at the C2S and/or C2OS connectors, consist of the following:
RS-232 170
NAME DESIGNATION DESIGNATION ORIGIN FUNCTION
TXD BA PIN K (DI) 170 Digital data input
RXD BB PIN L (DO) Modem Digital data output
from modem
CTS CB PIN M (CTS) Modem Flags the 170 that the
modem is ready to
transmit data
RTS CA PIN J (RTS) 170 Signals the modem that
the 170 wants to
transmit
DCD CF PIN H (CD) Modem Flags the 170 that a
carrier signal is being
received
GND AB PIN N (GND) Both Circuit common
An off-the-shelf Hayes modem minimally requires the following additional signal lines to
implement full operation, for which support from a 170 ACIA is not available:
NAME DESIGNATION ORIGIN FUNCTION
DSR CC Modem Indicates that the modem is ready to
transfer data.
DTR CD Host Indicates to modem that host is ready
to communicate.
The Model SM2400 solves this problem by essentially ignoring DTR (See Configuration
Command &D). The factory default for DSR is always on (See &S). Since DSR is not
monitored by the 170, this only becomes an issue when the Model SM2400 is connected
to Data Terminal Equipment.
From a system perspective, the modem has basically three interfaces With the outside
world.
1. Power Supply Edge Connector P1
2. RS-232 Edge Connector P1 or DB-9 J14
3. Phone Line RJ11-C Connector "LINE"