CP6100 I/O Process Programming Manual

Using CP6100: Managing Lines
For ADCCP only:
IDLETIMER. This parameter applies to the ADCCP protocol; it
determines the interval between passes through the poll list
for primary stations, and between idle RR frames for combined
stations. This value has a minor effect on the performance of
the line.
L1RETRY. This parameter specifies how often an operation is
tried at the link level before an error is reported to the
application. Too large a number of retries can mean a waste
of processing time; too small a value can reduce the number
of requests completed successfully.
L2RETRY. This parameter specifies how often an operation is
tried at the protocol level before an error is reported to
the application. Too large a number of retries can mean
a waste of processing time; too small a value can reduce
the number of requests completed successfully.
MAXFRAME. This parameter determines the largest frame that
ADCCP can transmit on the line. This number can exceed
the value of the CLBFRAMESIZE parameter. The larger the
frame size is, the more buffer space is required; the smaller
it is, the greater the overhead per byte of application data.
STATIONS. This parameter specifies the maximum number of
stations on the line. For each station, ADCCP reserves a control
block (about 26 bytes) on the LIU. Putting many stations on the
same line can affect efficiency, partly because of the buffer
space each line consumes on the LIU.
TWA. This parameter selects two-way alternate frame
transmission. The altenative is two-way simultaneous frame
transmission. In general two-way simultaneous transmission is
better for performance, because a station can send and receive
at the same time. On the other hand, some devices support
only two-way alternate transmission.
WINDOW. This parameter determines the number of I-frames a
station can send before receiving an acknowledgement from the
other station. If no errors occur, the larger the window, the
higher the throughput, because the application doesn't have to
wait as often before it transmits a frame. On the other hand,
if errors occur, recovery might involve repeating a larger
transmission.
October 1985
3-33