National Instruments NI-488.2 NI-488.2 User Manual

Chapter 8 NI-488.2 Programming Techniques
© National Instruments Corporation 8-9 NI-488.2 User Manual
// Convert the data into a numeric value.
sscanf (ReadBuffer, "%f", &Readings[ReadingsTaken]);
// Display the data.
printf(“Reading : %f\n”, Readings[ReadingsTaken]);
ReadingsTaken += 1;
if (ReadingsTaken >= 1000) {
return 0;
}
else {
// Issue a request to the device to send the data and rearm
// callback on RQS.
LocalIbsta = ibwrt (LocalUd, "SEND DATA", 9L);
if (LocalIbsta & ERR) {
printf ("ibwrt failed. No more callbacks.\n");
DeviceError = TRUE;
return 0;
}
else {
return RQS;
}
}
}
Writing Multithreaded NI-488.2 Applications
If you are writing a multithreaded NI-488.2 application and you plan
to make all of your NI-488.2 calls from a single thread, you can safely
continue to use the traditional NI-488.2 global variables (
ibsta, iberr,
ibcnt, ibcntl). The NI-488.2 global variables are defined on a
per-process basis, so each process accesses its own copy of the NI-488.2
globals.
If you are writing a multithreaded NI-488.2 application and you plan to
make NI-488.2 calls from more than a single thread, you cannot safely
continue to use the traditional NI-488.2 global variables without some form
of synchronization (for example, semaphores, mutexes, critical sections).
To understand why, refer to the following example.

National Instruments NI-488.2 NI-488.2 Specifications

General

Operating Systems	Windows, Linux, macOS
Programming Languages	C, C++, Python, LabVIEW
Interface	GPIB
Supported Standards	IEEE 488.2
Functionality	GPIB instrument control, data acquisition, and analysis

Summary

Chapter 1 Introduction

Setting Up and Configuring Your System

Describes how to set up and configure your GPIB system.

Chapter 2 Measurement & Automation Explorer (Windows)

Troubleshoot NI-488.2 Problems

Instructions for using the NI-488.2 Troubleshooting Utility.

Communicate with Your Instrument

Chapter 3 GPIB Explorer (Mac OS X and Linux)

Add a New GPIB Interface

View or Change GPIB Interface Settings

Chapter 4 Developing Your NI-488.2 Application

Interactive Instrument Control

Using the Interactive Control utility for instrument communication.

Choosing How to Use the NI-488.2 API

Guidance on selecting between traditional and multi-device NI-488.2 API calls.

Communicating with a Single GPIB Device

Checking Status with Global Variables

Explains how to use global status variables (ibsta, iberr, etc.).

Chapter 5 Debugging Your Application

NI Spy

Introduction to NI Spy utility for monitoring NI-488.2 calls.

Global Status Variables

Details on global status variables (ibsta, iberr, ibcnt, ibcntl).

NI-488.2 Error Codes

Explanation of error variable (iberr) and error codes.

Configuration Errors

Chapter 6 NI Spy Utility

Monitoring API Calls with NI Spy

Chapter 7 Interactive Control Utility

Chapter 8 NI-488.2 Programming Techniques

Termination of Data Transfers

High-Speed Data Transfers (HS488)

Describes the HS488 protocol for high-speed GPIB data transfer.

Enabling HS488

Instructions on how to enable the HS488 feature for GPIB interfaces.

Asynchronous Event Notification in NI-488.2 Applications

Using ibnotify for asynchronous notification of GPIB events.

Appendix C Error Codes and Solutions

GPIB Error Codes

Lists and describes GPIB error codes and their meanings.

EDVR (0)

Explains the EDVR error and provides solutions for accessing issues.

ECIC (1)

ENOL (2)