HP 5961-0509 manual Memory Status Request Example, Description Data, 16-2Status Readback

zFlush All Pages Command

zEcho Command

zStatus Readback Programming Hints

For status readback to work, the host system must contain a bi-directional driver to receive status response data. In network operations, some printing environments do not support bi-directional communication, such as many printer sharing devices which spool data, and some network operating systems. Applications designed to incorporate PCL status readback should be designed to function correctly in situations where no response is possible.

Note	For the stand-alone DOS personal computer, bi-directional
	driver/applications are required to access the parallel/serial I/O
	communication data for not only sending to the printer but also
	receiving data (status) back from the printer.
	FTo obtain status information you must initiate a request by sending
	either a request for memory status or a request for an entity status,
	as described on the following pages.

Memory Status Request

It is possible to identify the amount of available user memory using the memory status request. Being able to identify the available memory enables a user to determine whether sufficient memory is available for the entity being downloaded, potentially avoiding a printer memory overflow condition (control panel error 20, memory overflow).

An example memory request with its associated response is shown below.

Table 16-1 Memory Status Request Example

Description	I/O Data
Memory request (Free Space	EC*s1M
command) sent to printer from
host

16-2Status Readback EN