Dascom T2250 User Guide IGP for Dot Matrix Printers - Manual (Page 34)

IGP for Dot Matrix Printers User Guide
34
VFU Download Commands
VFU download commands are used with the IEEE 1284 and serial interfaces only. The VFU
Load not only sets values for the form length and bottom-of-form skip (see also, Skp Whn in
Chapter 2), but also sets up vertical tabs on the page that are used by VFU Channel Commands.
Load the printer VFU memory from your computer and then use VFU Channel Commands to
move the paper to specific locations. Your printer uses electronic memory for its VFU, allowing
the page format to be defined by commands from your computer up to a maximum storage of 255
lines.
Form lengths and vertical tab positions stored in the VFU memory are based on the Lines Per
Inch (LPI) setting in effect at the time the VFU is loaded. Settings are not affected by changes in
LPI or by entering Plot Mode.
VFU Load
To load the VFU, two escape sequences are needed, one to begin and one to end the load.
The VFU Load Command resets the current paper position as the top-of-form. Make sure the
paper is aligned at the desired top-of-form before sending the VFU Load Command.
To begin a VFU download, use the sequence:
ESC [ < 1 h
1B 5B 3C 31 68
To end a VFU download, use the sequence:
ESC [ < 1 l l = lower-case L
1B 5B 3C 31 6C
After the Begin-load escape sequence, all data, except ASCII control codes, is treated as VFU
formatting information and is placed in VFU memory. All ASCII control codes and Escape
sequences are ignored except the End-load sequence.
VFU Load Errors
All data must be in the proper VFU Load format. If an error occurs during the load or a load
overruns memory length, the load is canceled and any remaining VFU data is printed. Canceled
loads default to the current form length setting (as set from the control panel or with the FLS
Escape Sequence).
To use the Vertical Format Units you download you must send a Vertical Channel Command,
discussed below.