Table of Contents
Advertisement
NOTE
THE MUX CARD HAS A 128-BYTE ECHO BUFFER
FOR EACH PORT. IF THIS BUFFER SHOULD
OVERFLOW, ECHO INFORMATION WILL BE LOST,
ALTHOUGH
THIS
WILL
NOT
AFFECT
ANY
RECEIVE TEXT BUFFERS. AN OVERFLOW CAN BE
CAUSED BY THE CARD RECEIVING (LOTS OF)
DATA AFTER HAVING RECEIVED A DEVICE
X-OFF, OR NOT YET HAVING RECEIVED AN ACK
TO A HOST ENQ.
HP 27130A
Character echoing is enabled by setting the echo bit in the data block of the WCC, SF
L
Character
echoing may be toggled (on or off) for the duration of the request by setting the IItoggle echo ll bit in
the subfunction. Echoing is only available for full-duplex transmission mode.
The card will not echo single text termination characters. However, the card can be enabled
to echo a CR/LF for every CR received as a single text terminator by setting the lIecho CR-LF for
CR text terminator ll in the data block of the WCC, SF 9. By using the WCC, SF 27, you may select
which single text terminator in place of the CR to cause the CR -LF echoing.
Receiving Transparent or Binary Data
Transparent, or binary, data is defined to be data read with no processing by the firmware.
The
data is always terminated by using the End-On-Count option. All special processing such as soft-
ware handshake, edit mode, and single text termination should be disabled. This may be done by
changing the read configuration in WCC, SF 27; or by setting the read device data request sub-
function bits IItoggle editll, IItoggle signal ll , and IItoggle quoting ll as necessary.
Note that data errors (parity, framing, overflow) will terminate the record unless specifically
disabled (WCC, SF 31).
Function of Read Request Length
The read request will invoke special read processing when:
1.
No current receive record is available on the backplane and
2. alert 1 mode is disabled.
If the special read processing is invoked, the firmware will perform two different types of actions
depending on the status of the frontplane.
If the frontplane has a current record which can
satisfy the read request, the record will be terminated with the IItext terminated by card, no more
data
ll
code and be given to the backplane to satisfy the read request.
NOTE
If the read request has the S-bit set, any future read
requests will be satisfied by the remaining data in the
current record until the buffer is exhausted.
4-11
Advertisement
Table of Contents
