RC11xx(HP)-TM
RC25xx(HP)-TM
RC17xx(HP)-TM
2016 Radiocrafts AS
RC11xx(HP)/25xx(HP)/17xx(HP)-TM Data Sheet rev. 1.48 Page 19 of 86
2016 Tiny Mesh AS
Radiocrafts
Embedded Wireless Solutions
Transparent- and Packet Mode Functions
Serial Data Streaming
When streaming serial data from a Router Device or from a Gateway Device in Transparent Mode, the
data stream will automatically be divided into correctly sized Tinymesh
TM
RF packets before data is
transmitted in the mesh network. The Serial Data Input Buffer has a capacity of 256 bytes, allowing for
e.g. a complete MODBUS RTU packet to be received.
The Tinymesh™ module will signal a full buffer condition by setting the CTS output high, or by issuing
an Xoff character, as configured by the
UART FLOW CONTROL
parameter. The
SERIAL BUFFER FULL
MARGIN
parameter provides for an adjustable margin from the buffer full condition is signalled, until the
Serial Data Input Buffer overflows. The default setting of the
SERIAL BUFFER FULL MARGIN
parameter is
18 bytes, allowing the host MCU a margin of some additional bytes that may be transmitted before the
Serial Data Input Buffer in the module runs full. The default value of 18 bytes has been chosen to
optimize packet sizes when streaming data. Most host systems and terminal emulators will be able to
respond to the 'CTS off' status within the time needed to transmit two bytes. At this point, there will be
240 bytes received in the Serial Data Input Buffer, which is the maximum size of two full Tinymesh™ RF
packets.
The host MCU should stop transmitting data as soon as possible after detecting CTS off, or after
receiving the Xoff character. After a time period of a few milliseconds, as determined by the
SERIAL
PORT TIME OUT
parameter, the Tinymesh™ module will start forming new RF packets from the received
data, and initiate RF transmission.
If the serial data stream does not stop after the module has signalled the 'buffer full' condition, The
Tinymesh
TM
protocol stack will prepare the data for RF transmission immediately after a data buffer
completely full condition is present (256 bytes).
Note: Subsequent data delivered to the UART will then be lost if the data stream continues before the
module Serial Data Input Buffer is again available.
After successful transmission of the received data, the module will signal to the external MCU that the
Serial Data Input Buffer is again available, by setting the hardware handshake CTS signal low, or by
transmitting an Xon character.
Serial Port Handshake
The Gateway and Router serial ports (UARTs) offer several optional handshake settings to support
reliable connections to an external host controller. The different settings are available by changing the
UART FLOW CONTROL
parameter in
CONFIGURATION MEMORY.
The
UART FLOW CONTROL
parameter is a bitmap of control mechanisms that may be individually
enabled by setting the corresponding bit. To combine settings, add the values in the 'Bit Value' column
and enter the sum value into the
UART FLOW CONTROL
parameter in
CONFIGURATION MEMORY
.
Bit
No
Bit
Val-
ue
De-
fault
Name
Applies
to
Function
0
1
1
CTS
Router
and
Gateway
The CTS control signal will be low when the module is ready to receive
data. The external host should monitor the CTS line before transmitting
any data, as the module will discard data received while CTS is high.
The
SERIAL BUFFER FULL MARGIN parameter in Configuration Memory
may be used to set CTS off a number of bytes before the buffer is
completely full, thereby allowing the host system time to respond to the
CTS off situation. This function is important when for instance using
hardware handshake on a system with USB serial ports.
1
2
0
RTS
Gateway
The RTS control signal may be used by an external host to signal that the
host is ready to receive data. When enabled, the module will observe the
RTS line before transmitting any byte. No data will be transmitted while
RTS is high.
Note: If RTS is enabled, and the host does not set RTS TRUE (Low), a
connected Gateway Device will not be able to deliver data, and
consequently the Gateway will not receive data from the mesh network.
The mesh network will disconnect
.
2
4
0
RXTX
Router
and
The RXTX mode is provided for direction control of RS485 drivers. When
RXTX is enabled, the module UART will set CTS HIGH during data
