Gossen THERMAL GRAPHICS PRINTERS IPP 144 - 40 G - Manual (Page 34)

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Improved handshaking for pre-stored texts
After receiving the control command the printer now
sets RTS at „BUSY“ or the signal XOFF is transmitted.
When the printing of pre-stored text is complete, RTS is
reset or the signal XON is transmitted.
This handshake can be used to control the data
transmission and prevent rapid text calls being lost or
overwritten.
Note:
Without Handshake the following can occur, if the text
calls are sent in too quickly:
Data input:
1 2 3
Actual Print-out:
Machine No. 3 pre-stored Text No. 1
2 just „2“ printed, Text No. 2 missing
3 just „3“ printed, Text No. 3 missing
XON / XOFF
The report functions „Printer read/not ready“ are handled
by this protocol if no handshake lines are connected
(RS 232 C, RS 422 or RS 485).
This function only applies to the E version, interface II.
XON is transmitted if the IPP 144-40 GE is ready to
receive.
XOFF is transmitted if the IPP 144-40 GE is not ready
to receive (see above).
Note:
If the IPP 144-40 GE is not ready to receive, it transmits
this character just once, not continuously.
No adjustments have to be made, this protocol always
runs parallel to the hardware handshake.
During the preset wait delay the interface is not ready to
receive. After expiry of the wait delay the RTS signal
(or XON) becomes active again and requests the subse-
quent transmission.
The next interval begins upon receiving of or
. on its own is not accepted. Print
interval
(serial)