PSI BOX PLUS+ Reference
Control Functions
UNT.
Sends The Untalk Command.
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Purpose.
The UNTALK command is sent to the IEEE bus.
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The UNT command is to stop the current talker from
sending any more data. After an UNTALK command one device
must be TALKed before it can source any data.
The PSI BOX asserts ATN and becomes the active
controller, then the IEEE command UNT, hex 05Fh decimal 95,
is sent over the IEEE bus. After the command has been sent the
ATN remains true, PSI BOX is the active controller.
The UNT command is used automatically in the read
routine when data is read to the bus using the ENTER
command. It can be called separately to untalk all bus devices
prior to terminate a data transfer sequence. A TALK command
to a device other than the current talker automatically untalks the
active talker. The UNT command can also be sent by using
CMD 95 or CMD 223
Format.
UNT
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Params.
None.
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Returns.
None.
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Example.
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_
BUS UNT
Bus Activity.
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_
assert ATN if not already so
UNT
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Chapter 8
