Murata Electronics North America DNT500FP Manual Do Utilizador
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DNT900 - 11/05/08
remote is buffering more data than can be sent on one hop, it will send the remaining data in subsequent
hops. The remote adds its own address, a packet sequence number and error checking bytes to the data
when it is transmitted. These additional bytes are not output at the base station if the base is in transpar-
ent mode. When a transmission is received by the base station, it will be acknowledged if it checks error
free. If no acknowledgment is received, the remote will retransmit the same data on the next hop.
hops. The remote adds its own address, a packet sequence number and error checking bytes to the data
when it is transmitted. These additional bytes are not output at the base station if the base is in transpar-
ent mode. When a transmission is received by the base station, it will be acknowledged if it checks error
free. If no acknowledgment is received, the remote will retransmit the same data on the next hop.
2.5.2 Point-to-Mu ltipoint Network Operation
In a point-to-multipoint network, the base station is usually configured for protocol formatting, unless the
applications running on each remote can determine the data’s destination from the data itself. Protocol
formatting adds the address of the destination (remote) and other overhead bytes to the user data. If the
addressed remote is using transparent formatting, the destination address and the other overhead bytes
are removed. If the remote is using protocol formatting, the destination address and the other overhead
bytes are output with the user data.
applications running on each remote can determine the data’s destination from the data itself. Protocol
formatting adds the address of the destination (remote) and other overhead bytes to the user data. If the
addressed remote is using transparent formatting, the destination address and the other overhead bytes
are removed. If the remote is using protocol formatting, the destination address and the other overhead
bytes are output with the user data.
A remote can operate in a point-to-multipoint network using either transparent or protocol formatting, as
the base is always the destination. In transparent operation, a remote adds addressing, a packet se-
quence number and error checking bytes as in a point-to-point network. When the base receives the
transmission, it will format the data to its host according to its formatting configuration. A remote running
in transparent mode in a point-to-multipoint network will often have the MinPacketLength and TxTimeout
parameters set to non-zero values to reduce the chance of transmission collisions.
the base is always the destination. In transparent operation, a remote adds addressing, a packet se-
quence number and error checking bytes as in a point-to-point network. When the base receives the
transmission, it will format the data to its host according to its formatting configuration. A remote running
in transparent mode in a point-to-multipoint network will often have the MinPacketLength and TxTimeout
parameters set to non-zero values to reduce the chance of transmission collisions.
2.6 Full-Duplex Serial Data Communications
From an host application’s perspective, DNT500 serial communications appear full duplex. Both the base
station host application and each remote host application can send and receive serial data at the same
time. At the radio level, the base station and remotes do not actually transmit at the same time. If they did,
the transmissions would collide. As discussed earlier, the base station transmits a synchronization signal
at the beginning of each hop followed by its user data. After the base station transmission, the remotes
can transmit. Each base station and remote transmission may contain all or part of a complete message
from its host application. From an application’s perspective, the radios are communicating in full duplex
since the base station can receive data from a remote before it completes the transmission of a message
to the remote and visa versa.
station host application and each remote host application can send and receive serial data at the same
time. At the radio level, the base station and remotes do not actually transmit at the same time. If they did,
the transmissions would collide. As discussed earlier, the base station transmits a synchronization signal
at the beginning of each hop followed by its user data. After the base station transmission, the remotes
can transmit. Each base station and remote transmission may contain all or part of a complete message
from its host application. From an application’s perspective, the radios are communicating in full duplex
since the base station can receive data from a remote before it completes the transmission of a message
to the remote and visa versa.
2.7 Channel Access
The DNT500 provides two methods of channel access: CSMA or TDMA. Each method supports several
options as shown in the table below. The channel access setting is distributed to all remotes in the base
station status packet, so changing it at the base station sets the entire network. Carrier Sense Multiple
Access (CSMA) is very effective at handling packets with varying amounts of data and/or packets sent at
random times from a large number of remotes. The DNT500 includes a CSMA polling mode for coordi-
nated remotes and a CSMA contention mode for uncoordinated and/or reporting remotes. Time Division
Multiple Access (TDMA) provides a scheduled time slot for each remote to transmit on each hop. The
default DNT500 access mode is TDMA dynamic mode.
options as shown in the table below. The channel access setting is distributed to all remotes in the base
station status packet, so changing it at the base station sets the entire network. Carrier Sense Multiple
Access (CSMA) is very effective at handling packets with varying amounts of data and/or packets sent at
random times from a large number of remotes. The DNT500 includes a CSMA polling mode for coordi-
nated remotes and a CSMA contention mode for uncoordinated and/or reporting remotes. Time Division
Multiple Access (TDMA) provides a scheduled time slot for each remote to transmit on each hop. The
default DNT500 access mode is TDMA dynamic mode.