Black Box IC026A-R2, IC026AE-R2 manual Switch SW2 Enabling or Disabling Talk-Back on Timeout

RS-232↔IEEE 488 INTERFACE CONVERTER

4.4.2TALK-BACK ON TIMEOUT

SW2-2 selects whether the interface converter should address the attached bus device to talk when the interface converter has no more serial data to send. This feature relies on time and not on terminators. Its use is primarily for simulating a serial plotter from an IEEE 488 (HP-IB) plotter. The factory default is Talk-Back On Timeout enabled.

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Switch

Side

View

DOT

Talk-Back on	Talk-Back on
Timeout Disabled	Timeout Enabled

Figure 4-3. Switch SW2: Enabling or Disabling

“Talk-Back on Timeout.”

If Talk-Back on Timeout is enabled, the interface converter waits approximately 100 milliseconds after it detects that its serial input buffer is empty. If no serial character has been received by the end of this time, the IEEE bus device is addressed to talk. The choice of talk-back modes depends strongly on the type of device and software being used. For most plotter applications, the Talk-Back on Timeout feature should be enabled.

When the last IEEE bus terminator is detected from the IEEE device, the interface converter disables the device from sending additional information by asserting Attention (ATN) on the bus. If the IEEE device does not respond or finish transmission by the time additional characters are received into the serial input buffer, the talk sequence will be aborted to allow additional serial information to be sent to the IEEE device.

Most IEEE 488 plotters will not respond to the talk address sequence with output data unless there has been a specific device dependent command sent to tell them what to say. If they have not been told what to say, they say nothing.

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