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MSS User Guide 7: Pinouts
7-4
Modem Wiring
DSR (Data Signal Ready) versus CD (Carrier Detect)
By default, most modems assert CD only during a valid connection. In this case the
modem’s CD pin may be wired to the Server’s DSR pin. Alternately, many modems can
be configured such that DSR acts like CD. In this case, the modem’s DSR pin may be
wired to the Server’s DSR pin.
DTR (Data Terminal Ready)
The MSS normally asserts DTR. When modem control is enabled on the MSS, the server
will de-assert DTR for three seconds each time the port is logged out and each time a
user disconnects from a modem service. The modem must be configured to hang up and
recycle when DTR is de-asserted. If the modem is not configured in this way, sessions
may not be properly disconnected.
In this case, the modem’s DSR pin may be wired to the Server’s DSR pin.