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January 2004
3. When receiving from the serial port, a DC1 (0x11 Xon) is sent first. This code is used to turn on a
paper reader.
4. When receiving from the serial port, a DC3 (0x13 Xoff) is sent after the last
%
is received. This
code is used to turn off a paper tape reader.
Note that the Setting 14 selection XON/XOFF is similar to the DC CODES selection. Both of these settings
use the DC1/DC3 XON/XOFF codes to start/stop the sender when data is received too fast. When DC CODES
is selected for Setting 14 (synchronization), serial port #1 will transmit an XON (DC1) if a character has not
been received for five (5) seconds.
XMODEM may also be selected in setting 14. It is a receiver-driven communications protocol that sends data
in blocks of 128 bytes. Setting
synchronization
to XMODEM gives your RS-232 communication an added
level of reliability because each block is checked for integrity. If the receiver determines that the most recently
sent block is in error, it will request that the sender try to send the block again.
In order to use XMODEM, parity must be none, and RS-232 data bits must be set to 8. Also, the computer that
is sending the data must be equipped with a communications package that supports the XMODEM protocol. It
must be set to XMODEM to operate.
This version of XMODEM supports
check sum
verification only. Also, 512 bytes of memory must be available
before using XMODEM with DNC. XMODEM must use 8 data bits and no parity.
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