User Manual
Ports Serial Signals
8-22
8.12.1 DSR (Data Set Ready)
8.12.1.1 DSR for Automatic Logouts
An SCS port can be configured to automatically log itself out when DSR is no longer asserted; in other
words, the port will log out when the modem is disconnected. This can help ensure port security; users will
be prevented from unplugging terminal lines and using sessions that are still active. See Automatic Logouts
on page 8-10 for more information.
8.12.1.2 DSR for Controlling Remote Logins
The DSR signal can also be used to determine whether or not a remote login to a port will be permitted.
When enabled, the Signal Check characteristic will require the assertion of the DSR signal before a remote
login is permitted on a particular port.
Signal check is generally enabled for use with printers; if the printer doesn’t assert the DSR signal, it’s
assumed to be disconnected or powered off. In this case, the remote login isn’t permitted, and print jobs are
not sent from the SCS to the printer.
To enable Signal Check, use the following command:
Figure 8-51: Enabling Signal Check
8.12.2 DCD (Data Carrier Detect)
The DCD signal is asserted by the local modem when it detects a connection from a remote modem. If
you’re using a DB25 port, no wiring is required in order to use the DCD signal.
RJ45 ports have one pin that can be used for either DSR or DCD. If you are using modems, this pin must
be wired to the modem’s DCD pin. If you are using another type of device (such as a terminal or printer),
this pin should be wired to the device’s DSR pin. Refer to the Pinouts appendix of your Installation Guide
for instructions.
8.12.3 DTR (Data Terminal Ready)
The SCS asserts DTR when it is ready to accept incoming data or connections. It also uses DTR to cycle
the modem when modem control is enabled by temporarily dropping the signal.
SCS ports can be configured to assert DTR only when a user logs into the port by enabling the DTRWait
characteristic. See Set/Define Ports DTRWait on page 12-63 for details.
Local>> DEFINE PORT 3 SIGNAL CHECK ENABLED