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Communications protocol – PSC Scanners User Manual

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16

User’s / Programming Guide

If your system requires a WORD length of 8 bits and 1 or 2 STOP bits,
but no PARITY, select the option below:

PARITY check is not possible with this combination of STOP bits and
WORD length.

Some receiving equipment requires inverted serial communication
signals.

CD

Inverted Serial Communications

Communications Protocol

XON/XOFF

Protocol controls data flow between your PSC scanner and a serial
host computer. If Protocol = XON/XOFF is selected, the scanner rec-
ognizes 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. In
other words, when the receiving device is unable to accept data, it
sends on 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. An advantage of
this protocol is that additional hardware is not required for imple-
mentation; only transmit, receive, and signal ground are required.

Table 3. 8 Bit, No Parity

8

1

None

EM

8

2

EN