Rockwell Automation 2755-G6-D Scanner with RS-232 Option - Manual (Page 49)

Serial Communication Parameters
Chapter 6
6–7
Protocol controls data flow between your scanner and
the serial host computer. The protocol options are:
None, XON/XOFF, CTS, RTS.
XON/XOFF
When selecting XON/XOFF protocol, the scanner
recognizes the ASCII XON/XOFF characters. The
host may then stop transmission with XOFF and
resume with XON.
Controlled data flow is achieved between devices
when the receiving device sends ASCII XON/XOFF
codes to the transmitting device. When the receiving
device is unable to accept data, it sends an XOFF
code to inform the host to temporarily suspend data
transmission. When the receiving device catches up,
it sends an XON code to inform the host that it is
again ready to accept data.
XON/XOFF protocol does not require additional
hardware for implementation; only transmit, receive,
and signal ground are required.
CTS Protocol
Like XON/XOFF protocol, CTS protocol is a
mechanism used to control data flow out. The CTS
input is used to inform the scanner that the host
terminal is ready to accept scanned data.
When CTS (+) protocol is selected, the scanner
waits for a high level on its CTS input before
transmitting data.
When CTS(–) is selected, the signal polarities are
reversed and a low level indicates data may be
transmitted. The CTS protocol may be programmed
independently of the RTS protocol, however the
signal polarities must be the same. You may not
select CTS(+) and RTS(–).
Note: CTS protocol cannot be used if external
triggering is enabled. See page 5–8 for details.
Protocol