HP 8642A - Page 200

Operation
Model 8642A/B
Operating Messages (cont'd)
HP-IB
Codes
Comments
Keys
MSSG
Codes
MG
MSSG
Queued Up Messages
The instrument is constantly checking its status and updating its current message list
appropriately. However, the current message list is different from the copied message
list that you can access. The current message list always reflects the current state of
messages. However, this list cannot be viewed directly. Only a copied message list can
be viewed. You always copy the current list into the copied list to view the queued up
messages. (At first reading, this process may sound a bit confusing. Read on for more
confusion.)
Some messages are transient and will be cleared from the current list when the
condition they reflect no longer exists. (An example is "RECALL ERROR FOUND
.H10"). If for some reason you want to re-display such transient messages or handle
them via HP-IB, you could read the copied list since the current list would no longer
contain that message.
• To copy the current message list into the copied message list and view the first
message:
Select ( MSSG") (HP-IB: MG) (when the message list is not already being scrolled
through with the [ MSSG 1 key). At this time, all transient-type messages will be
deleted from the current message list. (Note: This could also cause transient hardware
and service messages to be deleted from the current message list.)
• To re-read the copied message list and view the first message:
Select rSTHlFT"! fMSlaG"] (at any time) to begin scrolling through the copied message
list.
e To continue reading messages, scroll through the copied message list:
Select [ MSSG"] repeatedly until the display of "END OF MESSAGE LIST .00".
Selecting ( MSSG 1 again brings back the normal display of instrument settings.
For example, let's say that you are not currently viewing the copied message list and
the MSSG annunciator is being displayed due to the transient message "RECALL
ERROR FOUND .H10" being queued up for display (because sometime in the past you
recalled an undefined register). To view that message, you need to copy the current
list into the copied list. So you press the rMBSGTl key (which deletes the transient
message from the current message list) and read all the messages. The message you
were being signaled to read was a transient message so when you press nvTS~SG~1 once
more after seeing the "END OF MESSAGE .00" message (which brings back the
normal display of instrument settings), the MSSG annunciator is no longer displayed.
If for some reason you want to re-read that message, you can read the previously
copied list by selecting 1 SHIFT"] rM55~G"~). If you select rM~S"S~G~l alone, you will lose
that message and copy the current message list into the (new) copied list.
The following messages indicate that no messages are queued up or the end of the
message list has been reached. To HP-IB users, the following messages indicate that
whenever you read back a 0 as a message code number, you know you are finished
reading the copied message list.
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