Measurement Computing Serial488/4 - Manual (Page 21)

Section 2 Getting Started
2.9
2.3.3 IEEE 488 Bus Terminator Selection
The terminating characters sent when status is output by the
Serial488/4 are set by using the T erminator (Yn) command. As shipped
from the factory, the unit's power on IEEE 488 bus terminators are CR LF.
The power on default terminators can be changed to any of the
four
available options discussed in detail in the Command D escription section.
The four available terminator command options are : CR only (Y0), LF
only (Y1), CR LF (Y2), and L F CR (Y3). If it is desired to have
particular power on default terminators, the terminators are set using the
Terminator Command and then saved
using the Save Configuration
command (S1).
The Serial488/4 ignores all terminators received from the host
controller on the command address. O nly the Execute command (X) is
used to signal the Serial488/4 that a command string has been completed.
The Serial488/4 ignores all terminators sent to the serial data address(es),
but will monitor the serial data it receives for the character specified with
the Serial Terminator command (Tn). If enabled by the Data EOI
command (Ln), EOI will be asserted when the serial terminator character is
sent to the host controller. E ach serial port may use a separate serial
terminator.
2.4 Memory Usage
Memory in the Serial488/4 is dynamically allocated for the serial input and
output buffers. This allows for the most efficient utilization of memory for any given
application. This memory is kept in the U SER 'heap' (a vernacular for heap of
memory) until required by the system.
At power on each serial port is allocated tw o 127 byte mini-buffers or queues,
one for input and the other for output. W hen the serial port requires more buffer
space, additional queues are allocated. W hen a queue is emptied, it is released from
the serial port so that it may be reallocated when, and where required.
There are approximately 430 queues available for a total of over 54,000 bytes of