Chapter 4 Remote Interface Reference

RS-232 Interface Configuration

DTR / DSR Handshake Protocol

The multimeter is configured as a DTE (Data Terminal Equipment) device and uses the DTR (Data Terminal Ready) and DSR (Data Set Ready) lines of the RS-232 interface to handshake. The multimeter uses the DTR line to send a hold-off signal. The DTR line must be TRUE before the multimeter will accept data from the interface. When the multimeter sets the DTR line FALSE, the data must cease within 10 characters.

To disable the DTR/DSR handshake, do not connect the DTR line and tie the DSR line to logic TRUE. If you disable the DTR/DSR handshake, also select a slower baud rate (300, 600, or 1200 baud) to ensure that the data is transmitted correctly.

The multimeter sets the DTR line FALSE in the following cases:

1When the multimeter’s input buffer is full (when approximately

100 characters have been received), it sets the DTR line FALSE (pin 4 on

the RS-232 connector). When enough characters have been removed to 4 make space in the input buffer, the multimeter sets the DTR line TRUE, unless the second case (see below) prevents this.

2When the multimeter wants to “talk” over the interface (which means that it has processed a query) and has received a <new line> message terminator, it will set the DTR line FALSE. This implies that once a query has been sent to the multimeter, the controller should read the response before attempting to send more data. It also means that a <new line> must terminate the command string. After the response has been output, the multimeter sets the DTR line TRUE again, unless the first case (see above) prevents this.

The multimeter monitors the DSR line to determine when the controller is ready to accept data over the interface. The multimeter monitors the DSR line (pin 6 on the RS-232 connector) before each character is sent.

The output is suspended if the DSR line is FALSE. When the DSR line goes TRUE, transmission will resume.

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Agilent Technologies 34401A manual DTR / DSR Handshake Protocol, Multimeter sets the DTR line False in the following cases
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34401A specifications

Agilent Technologies 34401A is a highly reputable digital multimeter (DMM), renowned for its accuracy, versatility, and performance in a wide range of measurement applications. First introduced in the early 1990s, the 34401A has become a staple in laboratories, manufacturing environments, and educational institutions due to its robust build and comprehensive features.

One of the standout characteristics of the 34401A is its impressive accuracy, boasting a basic DC voltage accuracy of 0.0035%, making it ideal for precise measurements in electronic testing. The multimeter offers a wide range of measurement capabilities, including voltage (DC and AC), current (DC and AC), resistance, frequency, and continuity test, making it a highly versatile tool for engineers and technicians.

The 34401A utilizes a 6½-digit resolution, enabling the user to measure small changes in electrical signals with remarkable precision. With a sampling rate of up to 1000 readings per second, it can handle dynamic test requirements, providing timely results without sacrificing measurement integrity.

In terms of connectivity, the Agilent 34401A includes a GPIB (General Purpose Interface Bus) for remote operation, allowing users to automate their testing processes and integrate the multimeter easily into larger measurement systems. This feature is particularly beneficial in automated test environments, where speed and accuracy are paramount.

Additionally, the DMM incorporates advanced measurement functions, such as statistical analysis, including mean, standard deviation, and minimum/maximum readings, which provide users with valuable insights into their data. The instrument's user-friendly interface, complete with a clear digital display and intuitive controls, enhances usability and ensures that users can easily navigate its various functions.

Robust software support further extends the capabilities of the Agilent 34401A. It is compatible with a range of software tools for data logging and analysis, enabling users to efficiently document and analyze their measurements over time.

In summary, Agilent Technologies 34401A stands out in the realm of digital multimeters due to its high accuracy, extensive measurement functionalities, and user-friendly features. Whether for research and development, quality control, or educational purposes, the 34401A remains a preferred choice for professionals demanding reliable and precise measurement solutions. Its enduring legacy in the industry speaks to its performance and reliability, making it an essential tool for anyone involved in electronic testing and measurement.
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