© Microhard Systems Inc.
Confidential
65
4.0 Register/Command Reference
In
PP/PMP
S115 determines the number of slots which are available
within a window of opportunity for Remote units to submit channel
requests to the Master modem. For a large number of remotes, the
value of S115 should be set relatively high:
Values (0 - 255)
3
S115 Repeat Interval
Remotes will randomly contend for the ability to access the channel request slots. For a small number of
Remotes, it is advisable to keep S115 closer to the default value so as to not ‘waste bandwidth’ by
maintaining a relatively large window housing a greater-than-necessary number of channel reservation
request slots.
In a TDMA-type system, S115 may be set to 1 as the Remotes are not able to request a transmission
channel: the Master polls each Remote for data.
Values (0 - 254)
5
S113 Packet Retransmissions
This register determines the maximum number of times that a packet
will be retransmitted (in addition to the initial transmission).
Retransmissions can be used to provide system robustness and to
ensure data delivery due to noisy environments or weak signal levels.
Retransmissions should not be used as the only means to correct for
data collisions. Retransmissions create additional traffic and can have
a significant impact on overall throughput of a system.
See register S213 for Repeaters.
Values (1 - 255)
S112 Packet Max Size
255
Determines that maximum number of bytes from the connected device
that should be encapsulated into a packet. Large packet sizes may
produce the best data throughput; however, a smaller packet is less
likely to become corrupted and, if it does, is retransmitted with a lesser
impact on network traffic.
The default setting of 255 bytes is suited to most applications in
frequency hopping modems.
In a PMP system, set
S113 to the minimum
value required as,
effectively, the data
throughput from Master to
Remote is divided by 1
plus the number stored in
S113.
Values (1 - 255)
S111 Packet Min Size
1
This is the minimum number of collected bytes in one buffer before the
buffer can be closed by the character timeout timer controlled by S116.
Typically should not be modified.
