Message Queues
HP 8163A Lightwave Multimeter, HP 8164A Lightwave Measurement System,
& HP 8166A Lightwave Multichannel System User's Guide, E1299
Returning the Instrument to Local
Control
If the instrument is in remote control, a screen resembling
Figure 1 will appear. Press [Local] if you wish to return the instrument to local
control.
Figure 1
Remote Control
Message Queues
The instrument exchanges messages using an input and an output queue. Error
messages are kept in a separate error queue.
How the Input Queue Works
The input queue is a FIFO queue (first-in first-out). Incoming bytes are stored in
the input queue as follows:
1 Receiving a byte:
– Clears the output queue.
– Clears Bit 7 (MSB).
2 No modification is made inside strings or binary blocks. Outside strings and
binary blocks, the following modifications are made:
Introduction to Programming
17