What is ARC ?

ARC stands for “Addressable RS-232 Chain” and is a low-cost system for linking instruments together so that they can be controlled and monitored by a personal computer. The ARC interface is an extension of the industry standard RS-232 interface and is exclusive to TTi instruments.
The interface differs from conventional RS-232 in that it allows multiple instruments (up to 32) to be controlled using the normal RS-232 or RS-422/423 port of a PC.

Why is there a need for ARC ?

The normal way of building up an automated instrumentation system is to use instruments fitted with a GPIB (IEEE-488) interface. The disadvantage of this is that GPIB instruments are relatively expensive, the GPIB controller is expensive, and the connecting cables are expensive.
ARC is intended to provide a low-cost alternative which utilises lower cost instruments, inexpensive cables, and can be controlled by any personal computer without the need for a special interface card or special software.
ARC will be particularly appropriate for applications where automated systems need to be constructed using general purpose bench-top instruments which may be regularly required for other purposes.
ARC is not intended as a competitor to GPIB which offers much higher data transfer rates and a more comprehensive range of facilities. GPIB continues to be supported by an extensive and growing range of TTi instruments.

How does ARC work ?

The ARC interface is basically an RS-232 interface with special extensions to the hardware and software.
Unlike normal RS-232 systems, each instrument can be assigned a unique address which allows the controlling PC to communicate with it individually. The instruments are “daisy chained” together using simple 2-core cables which are available from TTi or can be easily constructed using inexpensive parts.

What are the computer hardware and software requirements ?

The computer acting as the controller must have one free serial port. This can be RS232, RS423 or RS422.
An ARC system can be operated from any software that supports the computer's serial port. For optimum performance, X-on/X-off handshaking should be used.
Alternatively, TTi offer a low-cost** software package called ARC-TALK which runs on any IBM compatible PC and supports the full range of ARC capabilities.

Is ARC compatible with standard RS-232 ?
YES. The ARC interface can perform as a standard RS-232 interface when required. However, RS-232 instruments from other manufacturers can not be included within an ARC system.

Which instruments support ARC ?

TTi offers a full range of low-cost general purpose instruments which include the ARC interface as standard.
Currently the instruments offered are as follows:

PLP, TSXP and QLP series DC power supplies
1705 & 1906 digital multimeters
TF830 universal frequency counter
TG1010A DDS function generator
TGA1240 series arbitrary generators
TGR1040 synthesised RF generator
TA320S logic analyser

ARC technical specification

Interface connector: (instrument) 9-pin female D connector
Signals used: TXD, RXD, Ground
Handshaking: X-ON/X-OFF or None
Baud rates: 9600 default, other baud rates may be used
Word format: 1 start bit, 1 stop bit, 8 data bits, no parity

ARC-Windows Software

Features

ARC-Windows is a program that provides easy control of TTi ARC interfaced instruments from a Windows environment.  It will operate under Windows 95/98/ME/
2000 or XP.

It provides interactive windows operation with on-line help; a wide range of pre-programmed commands; Macro facilities via simple ASCII files and Response file generation.

ARC-Windows is available directly from TTi and from our agents and distributors.

Note:

The original DOS based version of this program called ARC-TALK  offers many of the same features but with a basic command line operation.  It is no longer available.

However, for customers who may wish to utilise ARC   functionality without purchasing ARC-Windows software, ARC-TALK can now be downloaded without charge from the Downloads page of the TTi website