RF Technologies ART400, Инструкция по установке, эксплуатации и программированию

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Commercial In Confidence
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3.16.4.2 MESSAGE DURATION
The time taken to transmit a message can be simply derived by multiplying the number of
characters in a message by the values given in table C making any appropriate corrections for
data format. The exception is 9600 baud where extra synchronisation sent during the message
must be taken into account, 8 synchronisation bits lasting a total of 8.3ms are sent after every
eighth message character.
3.16.4.3 TRANSMIT TO RECEIVE SWITCHING TIME
In full or semi-duplex operation transmit to receive switching time does not need to be
considered as the receive path is maintained during a transmission, in simplex operation
some time must be allowed to reload the transmitter synthesiser to stop it from interfering
with the receiver. The diagram below indicates the minimum time in which the radio is able
to receive a signal after completing a transmission.
symbol description
value
thold Period for which carrier is held up after sending last data byte 2.5ms + LOD
trxrdy Time to reload transmit synthesiser in simplex mode 6ms
During the time thold the radio transmits some padding bits to allow for propagation delays
in the receiving device before shutting off the carrier, this prevents possible chopping of the
message tail. The time thold is composed of a fixed 2.5ms period plus the programmable
value LOD (lead out delay). LOD is normally set to zero. After the time trxrdy has expired
the radio is ready to receive a new signal.
N.B. If RTS/CTS handshaking is not used the transmitter is turned on whenever data is
received at the serial port, the transmitter is left on until all buffered data has been
transmitted and no data has been input for a time equivalent to the length of two characters
at the radio baud rate (refer to table C). In general data transmitted by the radio is delayed
with respect to its receipt at the serial port by the receive to transmit switching time, if the
radio baud rate and serial port baud rate and both data formats are the same this delay
remains constant throughout the transmission. At the higher baud rates this delay is
generally greater than the lengthof two characters and so the procedure to stop transmission
is started as soon as the last character has been sent, at the lower baud rates however it is
possible that the time thold is extended while the radio waits for the two character timeout to
expire, this can also happen if data characters are not loaded back to back into the serial port.
3.16.5 RADIO DATA FORMATS
The radio signal can be set up to operate using 7 or 8 bit data, 1 or 2 stop bits, and odd, even
or no parity. This setting is independent of the serial port setup. This allows compatibility