Specifications

MDS 05-3438A01, Rev. E MDS 4790/9790 Series I/O Guide 39
a = Data bits (7 or 8)
b = Parity (N for None, O for Odd, E for Even)
c = Stop bits (1 or 2)
The factory default setting is 9600 baud, 8 data bits, no parity, 1 stop bit.
NOTE: 7N1, 8O2, and 8E2 are invalid communication settings.
If the data rate is faster than the radio’s baud rate setting, the
DATA Port
will accept a minimum of 500 data bytes in a single continuous data
transmission. At baud rates of 9600 bps or less, the radio can support
unlimited continuous data transmission. Under this condition, the
DATA
Port handshaking (CTS) would keep toggling on/off for a long transmis-
sion, or the buffer may be able to absorb the data for a smaller amount
of data. Mis-matched data rates should be avoided whenever possible.
Data Interface
Buffering
BUFF [ON/OFF]
This command displays or sets the received data handling mode.
Entering the
BUFF command alone shows whether the mode is seamless
(
ON), or fast byte throughput (OFF). Entering the BUFF command fol-
lowed by a parameter resets the received data handling mode. The
ON
parameter sets the radio to seamless data mode. The OFF parameter sets
the radio to fast byte throughput mode. The default is seamless data
mode.
The setting of this parameter affects the timing of received data sent out
the
DATA INTERFACE connector. Data transmitted over the air by the
radio is unaffected by the
BUFF setting.
If data buffering is set to
OFF, the radio will operate with the lowest pos-
sible average latency. Data bytes are sent out the
DATA INTERFACE port
as soon as an incoming RF data frame is disassembled. Average and typ-
ical latency will both be below 10 ms, but idle character gaps may be
introduced into the outgoing data flow.
If data buffering is
ON, the radio will operate in a seamless mode. That
is, data bytes will be sent over the air as quickly as possible, but the
receiver will buffer the data until enough bytes have arrived to cover
worst case gaps in transmission. A 2 ms delay may be introduced by data
buffering, but the radio will not create any gaps in the output data
stream. This mode of operation is required for protocols such as
MODBUS™ that do not allow gaps in their data transmission.
Note that seamless mode (
BUFF ON) is intended only for applications
where the transmitter’s baud rate is greater than or equal to the
receiver’s baud rate. Enforcement of this rule is left up to the user.
Data Buffering screen, Page 70
A
B