RV-M7 Technical Manual
61
Null modem with full handshaking
(DB-9 Female shown. Same wiring for male-to-male cable)
Connector 1
Connector 2
Function
2
3
Rx
Tx
3
2
Tx
Rx
4
6
DTR
DSR
5
5
Signal ground
6
4
DSR
DTR
7
8
RTS
CTS
8
7
CTS
RTS
15.5
Compatibility issues
The null modem cable with full handshaking does not permit the older way of flow control to take
place. The main incompatibility is the cross connection of the
RTS
and
CTS
pins. Originally, these
pins are used for a question/answer type of flow control. When the full handshaking null modem
cable is used, there is no request anymore. The lines are purely used for telling the other side if
communication is possible.
The main advantage of this cable is, that there are two signaling lines in each direction. Both the
RTS
and
DTR
outputs can be used to send flow control information to the other device. This
makes it possible to achieve high communication speeds with this type of null modem cable,
provided that the system has been designed for it.
16.
MIMIC Mode Overview
A MIMIC mode allows two or more M7s to mimic each other’s digital I/O. When in the MIMIC
mode, the M7 will periodically transmit its digital status. The M7 will also continue to operate as a
radio modem, sending/receiving data using pins 2&3 of the DB9, but the other I/O pins of the DB9
will be used for digital input/output.
Summary of Contents for RV-M7
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