AMT Datasouth PAL - Manual (Page 142)

_measurepage
136
Comments
Not all PAL printers can automatically measure the media, and those which can may not perform
all the measurements indicated. In printers that do not measure the media, the _measurepage
operator will simply return the current page settings.
Many printers must consume a certain amount of the media in order to measure it. In addition,
other PAL settings can influence the printer's ability to correctly measure the media. As a result,
the LimitArray and PagesInt parameters provide a limitation on how much media the printer
should consume. Not all printers will use PagesInt or all the entries in LimitArray. Some printers
can establish their own limits. On printers that do not actually measure the page but simply return
values, the PagesInt and LimitArray are ignored.
Pressure fed continuous media printers provide the primary reason for the existence of this opera-
tor. These types of printers use special sensors to detect the beginning and end of each page. Since
these printers use pressure rollers to advance the media, the media can slip very slightly in relation
to the printing mechanism. This slipping can result in some pages appearing slightly longer or
shorter in relation to other pages as the pages move past the sensors in the printer.
These printers must continuously adjust the feeding of the media in order to compensate for this
slipping. The printer calculates these adjustments based on the anticipated size of the media versus
the size measured by the sensors. In order to maintain accurate positioning of the media, the printer
must receive as accurate a media measurement as possible.
Unfortunately, varying media thickness and other variables can also result in pressure feed printers
not feeding the media in a consistent manner. As a result, different media types can introduce
different amounts of error.
By asking the mechanism itself to measure the media, the mechanism will automatically include
any error introduced by the media into the measurements. This will result in a measurement which
closely matches the anticipated operation of the media within the mechanism.
On pressure fed mechanisms, the programmer should specify a PagesInt value of around five or
more to ensure a reasonable level of consistency from one measurement to the next. Normal
measurement fluctuation on a pressure fed mechanism can often range as high as three points.
Excessively high fluctuations probably indicate sensor or other adjustment problems.