Intermec EasyCoder 501 E Installation & Operation Manual page 57

Chapter 7 Setting Up the Printer
Setup Parameters, cont.
Serial Communication,
cont.
56
• RTS/CTS
RTS/CTS is a protocol where the communication is controlled by
currents through separate lines in the cable being set either to high
or low. By default, this option is disabled.
RTS high indicates that the transmitting unit is able to receive
characters. RTS low indicates that the receive buffer is fi lled
to 75% (see XON/XOFF).
CTS high indicates that the unit transmitting the CTS signal
is ready to receive data. CTS low indicates that the receive
buffer is full (see XON/XOFF). In some computer programs,
for example MS Windows Terminal, RTS/CTS is designated
"Hardware."
• DTR
DTR ("Data Terminal Ready") is not controlled in the setup mode,
but by straps on the CPU board or interface board. DTR high
indicates that the transmitting unit is switched on.
• ENQ/ACK
In this protocol, the communication is controlled by the control
characters ENQ (ASCII 05 dec.) and ACK (ASCII 06 dec.) being
transmitted on the same line as the data. The sending unit transmits
ENQ at regular intervals. If the response ACK is not received,
the transmission is held up awaiting an ACK character from the
receiving unit. By default, ENQ/ACK is disabled.
• XON/XOFF
In this protocol, the communication is controlled by the control
characters XON (ASCII 17 dec.) and XOFF (ASCII 19 dec.) being
transmitted on the same line as the data. XON/XOFF can be
enabled/disabled separately for data received from the host by the
printer (printer sends XON/XOFF) and for data transmitted to the
host from the printer (host sends XON/XOFF).
XOFF is sent from the printer when its receive buffer is fi lled
to 75%, and the transmission from the host is held, waiting for
an XON character. When enough data have been processed so
the receive buffer is fi lled only to 50%, the printer sends an
XON character and the host resumes transmitting data. The same
principles apply to XON/XOFF sent by the host, even if the
percentage fi gure may differ.
By default, XON/XOFF is disabled for data both ways.
Intermec EasyCoder 501 E – Installation & Operation Ed. 1