Detecting an Unterminated Query Error When Using the TNT4882 ChipHardware: GPIB>>ASICs/OEM Products
Problem: I am developing an instrument based on the TNT4882 chip that I want to be IEEE 488.2 compliant. One 488.2 requirement is the detection and reporting of an Unterminated Query error. This requires that the application code can monitor for a brq (byte request) event, which occurs when the Controller in Charge (CIC) requests information from the TNT4882 chip. I tried several approaches to detect this event and the associated error condition, and I found that all of them either fail to detect the error condition reliably or cause erroneous Unterminated Query errors.Which registers should the application monitor to detect the brq event and/or unterminated query condition reliably? Solution: The Unterminated Query error occurs when the CIC attempts to read from an instrument without having first sent a complete and properly terminated query message. Refer to the IEEE 488.2 specification, Sec 6.x for more information about the definition of this error and the type of handling required.According to Chapter 3 of the TNT4882 Programmer Reference Manual (linked below), Interrupt Status Register 1 (ISR1) contains eight Interrupt Status bits. You need the bit DO - Data Out Interrupt Enable bit. Ignore the comment for One-Chip Mode: "DO is a don't care bit. Do not set DO IE. DO may read as 1 or 0." DO indicates that the TNT4882, as GPIB Talker, is ready to accept another data byte into the CDOR. This data byte is transmitted to the GPIB bus. DO clears when a byte is written to the CDOR or when the TNT4882 ceases to be the Active Talker. Related Links: Product Manuals: TNT4882 Programmer Reference Manual External Link: IEEE Standards Association Home Page Attachments:
Report Date: 02/28/2002 Last Updated: 05/12/2008 Document ID: 2IRF3QYY |
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