HP 61010A Owner's Manual page 38

Synchronous
Operation
Output - this field toggles between output ENABLED
and output DISABLED. The output field must indicate
ENABLED for any data to be sent to an external device.
Whenever the output is ENABLED, the data that is
currently stored on the internal data registers of the Digital
I/O is placed on the output bits. New data that is entered
when the output is disabled will still be stored; however,
it will not appear at the output until the output is enabled.
When this occurs, the ODAVcontrol signal pulses low for
approximately 10/is to indicate that the output data has
been sent. Output DISABLED deactivates all 16 output bits
(into a tri-state condition). The IHHHilf OUTPUTS, and
softkeys affect your instrument in the
same way as output ENABLED/DISABLED.
Operating your Digital Output synchronously
requires that when output data is sent to an external
device, the Digital Output signals the device that data is
available. After the external device accepts the data, it
returns a signal to the Digital Output to indicate it has
successfully received the information. Two control signals
— Output Data Available and Output Data Accepted — are
available at the output connector, both of which must be
connected to your external equipment (refer to Chapter 4).
Once the connections are made, you are ready to operate
your Digital Output synchronously.
The front panel graphics already discussed (i.e. output
value, base, length, start., logic sense, driver and output
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as they do in asynchronous mode. The only additional
fields that are used when operating your instrument
synchronously are the handshake and reset fields (see
Figure 3-5).
HANDSHAKE • must be ENABLED to operate your
instrument synchronously. The Handshake field toggles
between ENABLED and DISABLED. Point to and select
DISABLED to enable the control signals that allow
handshaking with your external equipment.
3-14 Manual Instrument Control