MDS 05-3438A01, Rev. F
MDS 4790/9790 Series I/O Guide
43
The setting of this parameter affects the timing of
received
data sent from the
DATA INTERFACE
connector. Data trans-
mitted over the air by the radio is unaffected by the
BUFF
setting.
If data buffering is set to
OFF
, the radio operates with the lowest possible
average latency. The radio sends data bytes from the
DATA INTERFACE
port as soon as it disassembles an incoming RF data frame. Average and
typical latency are both below 10 ms, but idle character gaps might be
introduced into the outgoing data flow.
If data buffering is
ON
, the radio operates in a seamless mode. That is,
the radio sends data bytes over the air as quickly as possible, but the
receiver buffers the data until enough bytes have arrived to cover
worst-case gaps in transmission. Data buffering might introduce a 2 ms
delay, 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:
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.
Continuous
Transmitter Keying
CKEY [ON/OFF]
The
CKEY
command enables or disables continuous keying. When
CKEY
is enabled (
ON
), the radio is continuously keyed. The
CKEY
command is
normally enabled when the radio is in a full-duplex master configura-
tion.
Data Interface
Clear-to-Send
Period
CTS [0-255
]
This command displays or sets the timer value associated with the CTS
line response. Entering the
CTS
(Clear-to-Send) command without a
parameter displays the timer value in milliseconds. Entering the
CTS
command with a parameter ranging from 0 to 255 sets the timer value in
milliseconds. The timer value function depends on the radio’s operating
mode (DCE or CTS Key). See the
DEVICE
command for more informa-
tion about these operating modes.
When the radio is in DCE mode, the timer specifies how long to wait
after the RTS line goes high before asserting the CTS line. A timer value
of zero means the CTS line will go high immediately following RTS.
Continuous Keying screen
,
Page 72
A
B
Clear-to-Send Delay screen
,
Page 70
A
B
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