Spread Spectrum Wireless Data Transceiver User Manual
LUM0002AG Rev D
Version 7.0
24
Modbus RTU Timing
The Modbus RTU setting causes the radio to wait for an amount of time, “gathering” data before sending
out the radio link.
With a setting of
0
(Disabled), the radio will send data out its radio link as soon as the data is received
into the serial port.
With a setting of
1
, the radio will wait for a number of slots equal to 2 times the Master Packet Repeat
setting before sending the received data out the radio link. For example, if
Master Packet Repeat = 3
,
the radio will wait for 6 slots, gathering data up the whole time. At the end of the 6 slots, the radio will
send all received data in one “burst”. This is the appropriate setting for most Modbus RTU devices.
With a setting of
2
and higher, the radio will wait for a number of slots calculated by the following formula:
(
Modbus RTU Setting
+
Master Packet Repeat Setting
+ 1) x 2
For example, in a radio where the Modbus RTU setting =
2
and the Master Packet Repeat setting =
3
, the
radio will wait for (2+3+1) x 2, or 12 slots.