32
MDS 4790M (MPT 1411) I/O Guide
MDS 05-3628A01, Rev. B
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 possible
average latency. Data bytes are sent out the
DATA INTERFACE
port as soon as
an incoming RF data frame is disassembled. Average and typical 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.
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 configuration.
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 information 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
that the CTS line will go high immediately following RTS.
When the radio is in CTS Key mode, the timer specifies how long to wait after
asserting the CTS before sending data out the
DATA INTERFACE
port. A timer
value of zero means that data will be sent out the data port without imposing a
keying delay. (Other delays may be present, depending on how other operating
parameters are configured.)
Should you experience problems with repeater operation after changing the
CTS
,
PTT
or
SCD
values, contact GE MDS.
Continuous Keying screen,
page 56
Clear To Send Delay screen,
page 55