Husky MP2500 Manual page 151

DSR
Use
To control the response to the DSR (Data Set Ready) handshake input on
COM2, while transmitting or receiving.
Notes
The connected device (usually a modem) can use this signal to tell the
MP2500 when it is ready to operate.
Setting Result
Yes
The MP2500 will transmit or receive only while DSR is
active (positive).
No DSR is ignored.
DTR
Use
To control production of the DTR (Data Terminal Ready) handshake output
on COM2, while transmitting or receiving.
Notes
This signal is provided to allow you to use auto-answer modems that
require DTR to be present before generating carrier.
Setting Result
Yes
DTR goes active (positive) when the MP2500 is ready to
receive or transmit.
No DTR remains inactive.
On DTR permanently on.
Chapter 13: Introduction to Communications 129