Envoy ACP/XF Application Programming Manual

Normal Response Mode (NRM) Protocols
EnvoyACP/XF Application Programming Manual–132179
3-6
Timers and Number of Retries
EnvoyACP/XF waits the amount of time specified in the poll interval for the next
WRITE request. If the poll interval expires before another WRITE request is received,
EnvoyACP/XF transmits an RR frame with the poll bit set.
EnvoyACP/XF allows you to select either a 1-octet or 2-octet control field. The number
of pending WRITE requests allowed depends on the control-field size:
Use the 2-octet control field for multiple OPEN calls. The window size, which can be
smaller than the modulo, imposes an upper limit on the number of pending requests.
Timers and Number of Retries
When transmission errors occur, EnvoyACP/XF always retries the requested operation.
SDLC and ADCCP-NRM use timeouts to detect errors. EnvoyACP/XF supports the
timeouts shown in Table 3-1
1-octet control field ð 7 WRITE requests (or write portions of WRITEREAD
procedures) can be pending at the link level at any given
time.
2-octet control field ð 127 WRITE requests (or write portions of WRITEREAD)
can be pending at the link level at any given time.
Table 3-1. Timers and Number of Retries
Features
Default
Value Modifier
SETMODE
procedure Description
Timeout 5 seconds T1TIMER SETMODE
15
For a primary station,
T1TIMER determines the
period that the station waits to
receive a response from the
secondary station before
sending an RR-frame with the P
bit set. The T1TIMER does not
begin until a frame with the P
bit set has been sent.
For a secondary station,
T1TIMER determines the
period that the station waits to
receive a poll from the primary
station before EnvoyACP/XF
issues a timeout error.