Campbell DCSCOM User Manual

DCSCOM

Telephone Modem

User Guide

Issued 1.3.99

Copyright

1999 Campbell Scientific Ltd.



Guarantee

This equipment is guaranteed against defects in materials and
workmanship. This guarantee applies for twelve months from date of
delivery. We will repair or replace products which prove to be defective
during the guarantee period provided they are returned to us prepaid. The
guarantee will not apply to:

• Equipment which has been modified or altered in any way without the
written permission of Campbell Scientific

• Batteries

• Any product which has been subjected to misuse, neglect, acts of God

or damage in transit.

Campbell Scientific will return guaranteed equipment by surface carrier
prepaid. Campbell Scientific will not reimburse the claimant for costs
incurred in removing and/or reinstalling equipment. This guarantee and the
Company’s obligation thereunder is in lieu of all other guarantees,
expressed or implied, including those of suitability and fitness for a
particular purpose. Campbell Scientific is not liable for consequential
damage.

Please inform us before returning equipment and obtain a Repair
Reference Number whether the repair is under guarantee or not. Please
state the faults as clearly as possible, and if the product is out of the
guarantee period it should be accompanied by a purchase order.
Quotations for repairs can be given on request.

When returning equipment, the Repair Reference Number must be clearly
marked on the outside of the package.

Note that goods sent air freight are subject to Customs clearance fees
which Campbell Scientific will charge to customers. In many cases, these
charges are greater than the cost of the repair.

Campbell Scientific Ltd,

Campbell Park, 80 Hathern Road,

Shepshed, Loughborough, LE12 9GX, UK

Tel: [phone]

Fax: [phone]

Email: [e-mail]

www.campbellsci.co.uk

Contents

1. Introduction................................................................ 1

2. Installation.................................................................. 2

3. Power Requirements ................................................. 3

4. Troubleshooting.......................................................... 3

Appendix A. ‘AT’ Command Summary......................A-1

Figures

2.1 Modem Configuration...............................................................................3

1. Connector Pin Diagram...............................................................................2

2. Schematic Diagram of Datalogger-Modem Connections ...........................3

DCSCOM Telephone Modem

NOTE

The DCSCOM is based around the Dataflex Pocket Stradcom, a commercial BABT-approved
telephone modem. A summary of the features of the DCSCOM is given below.

Features of the DCSCOM include:

• Initiate and receive calls – full duplex at 1200 baud

• ‘AT’ command set

• Fitted with BT miniature modular telephone plug

• Pulse or tone dialling

• Direct connection to and powered by Campbell Scientific dataloggers using the interface

provided

• Signal level connects/disconnects 5V DC external power, minimising current drain

The DCSCOM, as configured, fully meets the BABT approval
requirements and responds to the industry standard Hayes ‘AT’
command set.

1. Introduction

The DCSCOM modem is fully Hayes compatible and can be used at 1200 baud to
both receive calls and initiate calls from the datalogger (using instruction 97). For
more information on datalogger programming refer to the description of
Instruction 97 in the datalogger manual.

The DCSCOM is powered from the 5V supply of the datalogger. Current con­sumption is 0.002mA when off-line and less than 30mA when on-line. The
interface allows the datalogger to switch the power to the modem on and off.
When the modem is switched off, incoming calls are detected by the datalogger
via this interface; the datalogger responds by turning on the modem to answer the
call.

The DCSCOM is connected to a Campbell Scientific datalogger via a special ‘D’
connector interface which plugs directly into the 25-way connector on the modem.
The design of the interface allows other devices (for example a Campbell
Scientific Storage Module) to be connected in parallel with the modem. The other
end of the interface is connected to the datalogger using the 9-pin subminiature
SC12 ribbon cable supplied. The pin-out of the connector is shown in Figure 1.
The pins used by the modem are as shown below. All levels are 0V for logic low,
5V for logic high.

1

DCSCOM Telephone Modem

NOTE

1. (input) +5V regulated supply

2. (input) Ground

3. (output) Ring: a logic high signifies a ring signal has been detected.

4. (output) Rx Data: serial data from modem

5. (input) Modem Enable: a logic high turns on 5V power to the modem. A
logic low shuts off 5V power to the modem.

6. No Connection

7. No Connection

8. No Connection

9. (input) Tx Data: serial data to the modem.

2. Installation

Figure 1 Connector Pin Diagram

The modem is designed to plug into a modern British Telecom modular telephone
socket. We do not recommend the connection of a telephone in parallel with the
modem as (by default) the modem will answer all incoming calls (see below).

If you intend to use the modem on a remote telephone line, we recommend that
you install lightning arrestors on the telephone line; note that the warranty on the
DCSCOM does not cover lightning damage. Please contact British Telecom or
Campbell Scientific for further details.

Once the modem has been connected to the telephone line, plug the special silver
25-way ‘D’ connector (marked ‘
the interface to the datalogger’s serial I/O port using the 9-way SC12 ribbon cable
supplied. A connection diagram is shown in Figure 2. When the datalogger is
turned on, the modem will answer an incoming call.

The modem will not answer the telephone if the datalogger is not
powered up.

DCSCOM INTERFACE’) into the modem. Connect

To check for correct operation, call the modem/datalogger from another telephone
using a modem connected to a PC running appropriate Campbell Scientific
datalogger support software. The DCSCOM detects the speed of incoming calls
automatically.

2

The ringer equivalence number (REN) of the DCSCOM is 3. For

NOTE

Telephone Socket

Modem

Interface Connector

SC12 Cable

Typical Datalogger

Storage Module, etc.
Serial I/O Port

correct operation you should ensure that the sum of the RENs for
all equipment connected to one telephone line does not exceed 4.
You can usually assume that British Telecom equipment has a REN
of 1 unless otherwise marked.

To BT Modular

User Guide

Spare connector for
connecting SM192

Special DCSCOM

Figure 2 Schematic Diagram of Datalogger-Modem Connections

2.1 Modem Configuration

The modem is supplied pre-configured for use with Campbell Scientific
dataloggers, and there are no user configurable switches inside the modem.

CAUTION

Opening the modem casing for any reason will invalidate the
warranty.

3. Power Requirements

The power requirements of the modem are given in Section 1. When not com­municating, power consumption is negligible. However, note that the on-line
consumption, although not great, is large compared to the datalogger’s normal
requirements. This must be taken into consideration when estimating the size of
battery pack needed to run the datalogger, especially if the datalogger is to be
called for long periods via the modem.

DCSCOM

4. Troubleshooting

If any of the telephone equipment is not operating properly, you should immediately
remove it from your telephone line and establish the cause of the problem.

For assistance in installation or for repair, please contact Campbell Scientific or
your local representative.

3

Appendix A. ‘AT’ Command Summary

This manual does not attempt to provide complete instruction on the ‘AT’ command set.
However, for convenience, the commands are summarised below. For most applications with
a Campbell Scientific datalogger and IBM PC compatible computer, the modem commands
are issued automatically by Campbell Scientific software. These commands apply only when
the modem is used as an originate modem, which is not the primary use of this modem.

Except as noted, all commands begin with ‘AT’ and end with carriage return. As an example,
the command ATDT5551212 followed by carriage return will tone dial the number that fol­lows the ATDT then go on-line and wait up to 30 seconds for the remote modem carrier. If
the carrier is detected the result code 1 will be returned, otherwise the result code 3 will be
returned and the modem will return to the command mode.

Commands

AT Prefix to all commands (except A/)
A/ Repeat last command (not followed by carriage return)
D Dial
P Pulse
T Tone

0..9 Telephone number digits
W Wait for another dial tone
; Return to command state after dialling
, Pause
Z Reset to default settings
A Answer without ring
H Hang up
O Go to on-line state

Commands to Change Default Modes

R Call an originate modem
B CCITT mode
B1 BELL 212A mode
C Carrier off
C1 Carrier on
E Commands not echoed
E1 Commands echoed
F Half duplex
F1 Full duplex
Q Return result codes
Q1 Disable result codes
Sr? What is the value in register r?
Sr=n Set register r to value n
V Digit result codes
V1 Word result codes

Result Codes

0 OK
1 Connect
2 Ring
3 No Carrier
4 Error

A-1

DCSCOM Telephone Modem

Registers

S0 Rings before auto-answer (0..255)
S6 Wait for dial tone (2..255 seconds)
S7 Wait for remote carrier (1..255 seconds)
S8 Comma pause time (0..255 seconds)
S10 Delay time between loss of carrier and hang up (1..255 in tenths of

seconds)

A-2