Chapter 5 Remote Interface Reference

Simplified Programming Overview

Using the READ? Command

The READ? command changes the state of the scan trigger system from the “idle” state to the “wait-for-trigger” state. Scanning will begin when the specified trigger conditions are satisfied following the receipt of the READ? command. Readings are then sent immediately to the instrument’s output buffer. You must then enter the readings into your computer or the instrument will stop scanning when the output buffer becomes full. Readings are not stored in the instrument’s internal memory when using the READ? command.

Note: Sending the READ? command is like sending the INITiate command followed immediately by the FETCh? command, except the readings are not stored in reading memory when using READ?.

If you send two query commands without reading the response from the

Cautionfirst, and then attempt to read the second response, you may receive some data from the first response followed by the complete second response. To avoid this, do not send a query command without first reading the response. When you cannot avoid this situation, send a Device Clear before sending the second query command.

Using the INITiate and FETCh? Commands

The INITiate and FETCh? commands provide the lowest level of control (with the most flexibility) of scan triggering and reading retrieval. Use the INITiate command after you have configured the instrument for a scan. Scanning will begin when the specified trigger conditions are satisfied following the receipt of the INITiate command. The readings are placed in the instrument’s internal reading memory (up to 50,000 readings can be stored; if memory fills, new readings will overwrite the first readings stored). Readings are stored in memory until you are able to retrieve them.

Use the FETCh? command to transfer all of the readings from reading memory to the instrument’s output buffer where you can read them into your computer. Note that the FETCh? command does not clear memory. You can send the FETCh? command any number of times to retrieve the same data in reading memory.

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