Справочник Пользователя для FreeWave Technologies Inc. 218151431519
760 Mhz Data Transceiver Users Manual
LUM0000XX Rev A
Version 1.0
22
The default setting of 0 disables this function, where as a setting of 1 enables RTS-CTS control.
RTS-CTS setting 2 is described in detail in the application note #5437 DTR to CTS Line Alarm Feature.
With an RTS to CTS setting of 1, the Master senses the RTS line prior to all scheduled packet
transmissions. If the state has changed, the Master will then transmit a message to the Slave with the
new status. This transmission will occur regardless of data being sent. If data is ready to be sent, the
RTS status message will be sent in addition to the data. In Point-to-Point mode, the Master will continue
sending the new status message until it receives an acknowledgment from the Slave. In MultiPoint mode,
the Master will repeat the message the number of times equal to the Master Packet Repeat value in the
MultiPoint Parameters menu.
transmissions. If the state has changed, the Master will then transmit a message to the Slave with the
new status. This transmission will occur regardless of data being sent. If data is ready to be sent, the
RTS status message will be sent in addition to the data. In Point-to-Point mode, the Master will continue
sending the new status message until it receives an acknowledgment from the Slave. In MultiPoint mode,
the Master will repeat the message the number of times equal to the Master Packet Repeat value in the
MultiPoint Parameters menu.
Master transmit times are completely asynchronous to the occurrence of any change of the RTS line; the
latency time from RTS to CTS is variable. The Max and Min Packet Size parameters in the Radio
Parameter menu determine this duration. Setting both parameters to their maximum value of 9 will
produce a maximum latency time of approximately 21 ms. At the minimum settings for Max and Min
Packet Size (0), the time will be approximately 5.9 ms. Please note that this latency can increase
significantly if packets are lost between the Master and Slave. In Point-to-MultiPoint mode, there is no
absolute guarantee that the state change will be communicated to all Slaves in the unlikely event that all
repeated packets from the Master do not get through to all Slaves.
latency time from RTS to CTS is variable. The Max and Min Packet Size parameters in the Radio
Parameter menu determine this duration. Setting both parameters to their maximum value of 9 will
produce a maximum latency time of approximately 21 ms. At the minimum settings for Max and Min
Packet Size (0), the time will be approximately 5.9 ms. Please note that this latency can increase
significantly if packets are lost between the Master and Slave. In Point-to-MultiPoint mode, there is no
absolute guarantee that the state change will be communicated to all Slaves in the unlikely event that all
repeated packets from the Master do not get through to all Slaves.
Note: If DTRConnect is enabled and set to 2, the RTS to CTS feature will not work.
Note: If the DTRConnect is enabled and set to 1, RTS to CTS mode takes precedence over the
functionality of the CTS line on the Slave relating to the DTRConnect feature.
Note: The RTS to CTS option is only available in RS232 mode.
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R
ETRY
T
IME
O
UT
The Retry Time Out parameter in a Slave sets the delay the unit will wait before dropping the connection
to a Master in MultiPoint mode. The factory default is set at the maximum of 255. The maximum setting
means that if 1 packet in 255 is sent successfully from the Master to the Slave, the link will be maintained.
The minimum setting is 8. This allows a Slave to drop a connection if less than 1 in 8 consecutive packets
is successfully received from the Master.
to a Master in MultiPoint mode. The factory default is set at the maximum of 255. The maximum setting
means that if 1 packet in 255 is sent successfully from the Master to the Slave, the link will be maintained.
The minimum setting is 8. This allows a Slave to drop a connection if less than 1 in 8 consecutive packets
is successfully received from the Master.
On the other hand, the function in the Master is effectively the same. With a setting of 255, the Master
will allow a Slave to stay connected as long as 1 packet in 255 is successfully received at the Master.
will allow a Slave to stay connected as long as 1 packet in 255 is successfully received at the Master.
The Retry Time Out parameter is useful when a MultiPoint network has a roving Master or Slave(s). As
the link gets weaker, a lower setting will allow a poor link to break in search of a stronger one.
the link gets weaker, a lower setting will allow a poor link to break in search of a stronger one.
Note: Setting Retry Time Out to 20 is recommended in areas where several FreeWave networks exist.
This setting will allow Slaves to drop the connection if the link becomes too weak, while at the
same time prevent errant disconnects due to interference from neighboring networks.
same time prevent errant disconnects due to interference from neighboring networks.
While intended primarily for MultiPoint networks, the Retry Time Out parameter may also be modified in
Point-to-Point networks. However, the value in Point-to-Point mode should not be set to less than 151.
Point-to-Point networks. However, the value in Point-to-Point mode should not be set to less than 151.
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L
OWPOWER
M
ODE
The Lowpower Mode feature allows a MultiPoint Slave to consume less power. This is achieved primarily
by dimming the transceiver's LEDs. When set to 2 through 31, the transceiver will sleep between slots.
For example, at a setting of 2 the transceiver sleeps 1 out of 2 slots; at a setting of 3 the transceiver
sleeps 2 out of 3 slots, and so on.
by dimming the transceiver's LEDs. When set to 2 through 31, the transceiver will sleep between slots.
For example, at a setting of 2 the transceiver sleeps 1 out of 2 slots; at a setting of 3 the transceiver
sleeps 2 out of 3 slots, and so on.
The following table shows the changes at different Lowpower Mode settings. The actual current draw
depends on many factors. The table below gives only a qualitative indication of supply current savings. A
low number reduces latency and a high number reduces current consumption.
depends on many factors. The table below gives only a qualitative indication of supply current savings. A
low number reduces latency and a high number reduces current consumption.