Printronix P3000 Series DVFU

5–7Vertical Format Units

DVFU

The DVFU may be selected in P–Series protocol and is generally used in conjunction with the

Dataproducts

interface. A maximum of 12 channels can be assigned to each physical line of a form—

to 143 lines. A channel number is assigned to each line on the form. The host computer sends

chan

nel codes to the printer, resulting in rapid paper slewing to the next corresponding line. The

programming

sequence follows this order: 1) start load code,

2) channel assignments,

and

3) end load

code.

The DVFU start load codes are either 6C, 6D, or 6E hex with the PI line high.

Start Load Code – 6C, 6D, or 6E Hex

Hex

– The DVFU start load code of 6E (hex) with the PI line high initiates the DVFU memory load

routine using the current printer line spacing as the DVFU line spacing.

Hex

– The DVFU start load code of 6C (hex) with the PI line high initiates the DVFU memory load

routine using 6 lpi as the line spacing, regardless of the current printer line spacing.

Hex

– The DVFU start load code of 6D (hex) with

the PI line high initiates the DVFU memory load

routine using 8 lpi as the line spacing, regardless of the current printer line spacing.

Channel Assignment

Following

the start load code, all data bytes received are interpreted as channel assignment data

until

the

end load code is received.

During the channel assignment portion of the load routine, the PI line can

be high or low; if high, however

, the channel data

cannot

be the same as start

end load code data. The

last

channel 12

loaded is assigned Bottom–of–Form (BOF). If skip–over perforation is enabled, slew

ing will occur from the bottom of the form to the top of the form.

maximum of 12 channels can be assigned to one physical line on the form (multiple channels per line

facilitate

the use of a single DVFU load for multiple forms). T

wo eight–bit data bytes (DVFU charac

ters)

are required per line. As shown in T

able 5–4, the least significant six bits of the first data byte are

used to assign channels 1 through 6; the least significant six bits of the second data byte are used to

assign channels 7 through 12. If a bit is set, the corresponding channel is assigned.

Each

line on the form requires two

bytes. For lines not requiring a channel identification, the two bytes

should

not contain channel assignments.

maximum

of 143 lines (286 DVFU bytes) can be assigned on the form. If the printer receives more

than

286 bytes without an end load code, the end load code is “forced” and the load routine is termi

nated.

CH 1 TOF – The first channel, line 1 of the form, must be assigned channel 1, top–of–form, or the

entire load sequence is ignored and the memory reset. Consequently, when preparing to load the

DVFU

memory

, position the paper at the required top–of–form position in anticipation of sending the

TOF

channel assignment code as the first line loaded. After the memory is loaded, a Form Feed code

(FF, 0C hex) moves the paper to the next channel 1 (top–of–form).

2 VT

– Channel 2 is designated as the vertical tab channel. After the memory is loaded,

a VT code

(0B

hex) moves the paper to the next channel 2. If the printer receives a VT code but channel 2 is not

loaded,

the paper advances a single line at the current line spacing.