User`s manual

EM1500 User’s Manual www.rabbit.com 101
C. GLOSSARY OF TERMS
Access Server
A network device that accepts telnet sessions, passing data received by a telnet client to a serial port,
and passing data received from the serial port to the telnet client. This is a more general term, replac-
ing the older term “modem server.”
AES
Advanced Encryption Standard is a symmetric (same key used to encrypt and decrypt) encryption
method. It is becoming the de facto standard, replacing the Data Encryption Standard (DES).
COM port redirector
A type of device driver that gives its host PC virtual serial ports. The driver traps calls to these virtual
ports to route to an IP address. When used in conjunction with the EM1500, this allows applications
that communicate with an attached device via a local serial port access to that same device over a
remote connection without making any programming changes! The application still thinks it is talking
via a local serial port.
A COM port redirector is a good solution for legacy software applications that you either can not or
will not modify. A Google search shows that there are many of these products available on the market
today.
CTS
Clear to Send, a hardware flow control signal driven by a DCE device to tell DTE device when to start
or stop.
DCE
Data Communication Equipment is a term that describes the pins of a serial connector and their signal
direction. Signal names are derived from the point of view of the connected device (DTE q.v.).
• Tx - input for data to be transmitted to non-local destination
• Rx - output for data received from non-local destination
• RTS - Request to Send, an input that tells the DCE that the DTE is ready to receive
• CTS - Clear to Send, an output that says the DCE is ready to receive
• DTR - Data Terminal Ready, an input to indicate readiness of DTE
• DSR - Data Set Ready, an output to indicate readiness of DCE
• DCD - Data Carrier Detect (aka., RLSD, Receive Line Signal Detect), an output that should be
asserted before sending
The EM1500 may be used as either a DTE device or a DCE device, depending on the serial port being
used. SER2 is a DCE device.