TDK Module blu2i - Manual (Page 27)

Pure Cable Replacement Mode 7
7.1 Data Cable
The module has the capability of being preset into a pure 5-wire data
cable replacement mode. The 5 wires being RX, TX, CTS, RTS and
GND. This mode requires no changes to a host application since the
Bluetooth connection is automatically set up on power up and will retry
when the connection drops.
By implication, two devices are needed to replace a cable. One device is
pre-configured to always be a master and the other, a slave.
Assuming the Bluetooth address of the master to be and
that of the slave to be , the master module is configured by
sending it the following AT commands.
AT&F
ATS512=1
ATS504=1
ATS507=2
ATS530=2000
AT&W
AT+BTR
Where the ATS507=2 setting puts the device in DSR drop mode only.
This means that when the device needs to be reconfigured, deasserting
the DSR line will ensure that the module responds quickly to AT
commands. This further means that in stand alone mode, the DSR input
line MUST be asserted e.g. 0v in TTL signal mode.
The slave is configured by,
AT&F
ATS512=4
ATS0=-1
AT&W
AT+BTR
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