British Telecommunications Engineering Volume 6 Part 4 page 285

First STEbus Modem

British Telecom Microprocessor Systems has launched the first STEbus-compatible modem which provides systems designers with an easy means of building remote STEbus control and instrumentation systems capable of communications over the public switched telephone network. The modem operates to V.21 or V.23 standards and has built-in intelligence to allow control by a high-level Hayes-like command protocol.

The modem, designated 4300 , comes on a single-Eurocard form-factor, integrated with a BT603A line connector inside a small shielded enclosure to conform to BABT requirements. LED indicators and a loudspeaker for line monitoring are also included in the package.

In addition to the standard V.21 /23 communication capability (300/300 or 1200/75 baud transmit/receive data rates respectively), the 4300 can switch under software command to a 75/1200 baud configuration for high-speed bidirectional data transmission. A further software-selectable option provides a back channel of 150 baud for use on leased telephone lines.

The high-level command set includes control over a wide range of modem functions including dialling, answering, operating mode, line monitoring transmit carrier, console echo, loopback, reset, identification request, and status codes.