User Manual

MHX-2400 Operating Manual: Chapter 3 Configuration Options 31
S Register 114 - Packet Size Control
This register, when set to 1, allows for Repeater and Slaves’ local S111 and
S112 to override those of the Master. This may be useful for controlled
asymmetrical data flow. The master always transmits in the first portion of
the hop interval, with slaves and repeaters responding back to the master on
the second portion of the hop interval. Setting the master’s max packet size
smaller than that of the slave would ensure that the master uses less of the
available time within the hop interval for transmitting data, thereby
allocating more time for the slave.
S Register 116 - Packet Character Timeout
This register has valid entries of 0 to 254 milliseconds. The Packet
Character Timeout timer looks for gaps in the data being received from the
DTE. The timer is only activated after the Minimum Packet Size has been
accumulated in the modem. After which, if the timer detects a gap in the
data exceeding the Packet Character Timeout value, the modem will
transmit the data.
The MHX-2400 will accumulate data in its buffers from the DTE until one
of the following requirements is met (whichever occurs first):
• The Maximum Packet Size (in bytes) has been accumulated;
• The Minimum Packet Size has been accumulated AND the Packet
Character Timeout interval has elapsed.
The default for the Packet Character Timeout is 9 ms. If set to 0 ms, the
unit will buffer exactly the minimum packet size before transmitting.
S Register 113 - Packet Retransmissions
This register applies to both Master Point-to-Multipoint and Repeater
operation. It does not apply to Slave or to Master Point-to-Point operation.
The Master will retransmit each data packet exactly the number of times
defined by the Packet Retransmissions parameter. The Master retransmits
once at the beginning of each hopping interval until the limit is reached.
This parameter is not necessary in Slave units since all Slaves receive
acknowledgement from the Master, and needn’t blindly retransmit if it has
knowledge that the Master has received the packet. Similarly, this
parameter is not used by the Master during Point-to-Point communication
since the Master only would be required to retransmit if no
acknowledgement were received from the Slave. As discussed previously,
the Repeater effectively behaves as both a Master and a Slave. When the
Repeater is tuned to its Secondary Hopping Pattern (acting as a Master), the
Packet Retransmissions Parameter comes into play. The Repeater will re-
send packets of data on to Slaves or other Repeaters exactly the number of
times defined by the Packet Retransmissions parameter.
Recipients of the packet will discard any duplicates The valid settings for
this parameter are 0 to 255 retransmissions. The default is 2.