HP Pcl 5 Manual

							ENRaster Graphics Example 15-33 Figure 15-11 Example of Raster Graphic Image Data
  
						

							15-34   Raster GraphicsEN 
						

							ENIntroduction  16-1
16
Status Readback
Introduction  
This chapter describes the PCL status readback features. 
PCL status is requested from the printer with the commands 
described in this chapter. Following a status request, the printer 
generates a status response. This response consists of ASCII 
data which is sent directly from the printer, through the I/O, back 
to the host. Status readback allows you to obtain information 
from the printer such as: available printer (user) memory, 
current available fonts and symbol sets, and the ID numbers 
of downloaded macros and user-defined patterns to verify 
their presence.
The contents of this chapter are listed below:
zIntroduction 
 Memory Status Request 
 Entity Status Request 
zStatus Response Syntax 
zSet Status Readback Location Type Command 
zSet Status Readback Location Unit Command 
zInquire Status Readback Entity Command 
zEntity Status Responses 
Font 
 Font Extended 
Macro 
 User-Defined Pattern 
Symbol Set 
zEntity Error Codes 
zFree Space Command 
 Memory Status Response 
 Memory Error Response  
						

							16-2   Status ReadbackEN z
Flush 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.
NoteFor 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 
command) sent to printer from 
host 
 E
C*s1M 
						

							ENIntroduction 16-3
Entity Status          
It is possible to request status for the printer’s entities. An entity is a 
font, symbol set, macro, or user-defined pattern stored in the printer. 
Each individual entity request is limited to one specific entity, and is 
further limited to a specific location. To request entity status, you must 
send the entity status readback commands to identify a location type 
and a location unit, and then send the entity request command.
Location type refers to the memory locations which store entities. 
These memory locations include internal ROM, RAM (for downloaded 
entities), cartridges, user-installable ROMs (SIMMs), and one 
additional location identified as “currently selected.“ Currently 
selected identifies the entity which is active, such as the font or 
user-defined pattern last selected. (Currently selected does not 
apply to macros or symbol sets).
Location unit refers to a specific location (or device) within the 
location type. For example, location unit “1” for location type 
“car tridge,“ identifies the left cartridge on a printer with two cartridges; 
or, unit “1” for location type “downloaded,” identifies the temporary 
fonts (as opposed to permanent).
The location type and unit are described in detail under the location 
type and unit status readback command descriptions provided later 
in this chapter.
Once the location type and unit are specified, the status can be 
requested using the Inquire Status Readback Entity command. 
This command identifies the entity (font, symbol set, macro, or 
user-defined pattern) and causes the printer to send the response.Status response sent from 
printer to hostPCL
INFO MEMORY
TOTAL=100000
LARGEST=25000 Table 16-1 Memory Status Request Example (continued) 
						

							16-4   Status ReadbackEN
A basic entity status request is shown in the example below. This 
example identifies a status request for downloaded permanent fonts. 
The example also includes a status readback response at the bottom. 
Note that this example shows only one possible request/response; for 
more detailed information, refer to the status readback command 
descriptions provided later in this chapter.
In addition to the normal status responses, if an invalid request is 
made, the printer returns an error response. Error responses are 
described under the Inquire Status Readback Entity command, later 
in this chapter. Table 16-2 Entity Status Request Example
OperationExample PCL 
Command Comments
Set location type 
 E
C*s4T This Set Location Type 
command sets the location 
type to “downloaded.”
Set location unit 
 E
C*s2U This Set Location Unit 
command sets the location 
unit to “permanent.”
Identify entity 
which initiates 
status readback 
(Inquire Entity) 
 E
C*s0I The Inquire Status Readback 
Entity command selects status 
for “fonts” and causes the 
printer to buffer the response.
Table 16-3
Printer 
status 
res- 
ponse
PCL
INFO FONTS
SELECT=“(8U(s1p__v0s0b4120T (7X”
SELECT=“(10U __v0s0b4157T(21X”Two permanent 
downloaded fonts 
exist in the printer: 
University Roman 
(4120T) and Dom 
Casual (4157T). 
						

							ENIntroduction 16-5
Status Response   
When the printer receives a status request (command), it processes 
that request and forms the response data. This data is then stored in 
an I/O status buffer. The response is saved in this buffer until it is 
either read (by any user) or the printer is turned off.
In addition to clearing the status buffer by reading the status response 
or by turning off the printer, status responses are cleared if one the 
following settings are changed:
zPrinter resolution (600/300) 
zPage protection 
zLanguage personality
Status requests and their associated response are processed in the 
order in which they are received.
The number of responses the printer can buffer varies, depending on 
internal printer operations. When requesting status, especially in the 
case where multiple applications or users are sharing one printer, HP 
recommends that you request one item, and then read its response 
prior to making another request.
NoteSince the printer may contain a status response requested by a 
previous application’s operation, it is important to use the Echo 
command (described later in this chapter) to synchronize your 
application’s request with the printer’s responses. Refer to the 
Echo command description and to the “Programming Hints” 
section at the back of this chapter for additional information. 
NoteThe number of status responses a printer can buffer varies from 
printer to printer. The HP LaserJet 4 printer can store 5 responses. 
Refer to the PCL 5 Comparison Guide for printer specific information.
A status response is returned to the printer I/O port from which it was 
requested. 
						

							16-6   Status ReadbackEN
Status Response Syntax  
All status responses start with the letters “PCL” followed by a 
Carriage Return control code (decimal 13; ) and a Line Feed 
control code (decimal 10; ). In addition, each remaining line of 
the response is terminated by a Carriage Return and Line Feed 
control code. Finally, status responses are terminated by a Form 
Feed control code (decimal 12; ). The basic syntax for the 
status response is shown below.
PCL
INFO TITLE
KEYWORDn=DATAn
KEYWORDn=DATAn
    M

TITLE, KEYWORDn, and DATAn are strings that vary depending on 
the particular status readback command being executed. Each status 
readback response has one or more keyword lines associated with it. 
A slight variation of this is the Echo command response. This 
response is shown below.
PCL 
ECHO ValueField 

ValueField is the decimal number taken from the Echo command 
value field.
NoteKeywords may be added for future printers that are not documented 
here. Applications that use status readback should be designed to 
ignore lines with keywords they do not recognize. 
Two example status responses are shown below.
PCL 
INFO MEMORY 
TOTAL=100000 
LARGEST=25000 
 
						

							ENStatus Response Syntax 16-7
PCL 
INFO FONTS 
SELECT=“(8U(s0p10.00h12.00v0s0b3T”
SELECT=“(0N(s0p16.67h8.5v0s0b0T”
SELECT=“(s1p__v1s0b4101T(78X”
SYMBOLSETS=“0D,0I,0N,0S,0U,1E,1F,1G,...”
SELECT=“(8U(s1p__v0s3b4148T”

NotesIn the example listings, “,” “,” and “” identify the 
Carriage Return (decimal 13), Line Feed (decimal 10), and Form 
Feed (decimal 12) control codes. The “” following the 
“SELECT=” keyword is a five character representation (the printable 
characters: “”) and does not identify an escape 
control code (decimal 27).
The examples in the remainder of this chapter do not show the status 
response line termination (“”) control codes, or the 
termination (“”) control code.
Example responses in this chapter for “SYMBOLSETS=” do not list 
the complete list of internal available symbol sets, only a partial list: 
“0D,0I,0N,0S,0U,1E,1F,1G,...” The internal symbol sets are printer 
dependent and may vary from printer to printer. Refer to the PCL 5 
Comparison Guide for printer specific information.  
						

							16-8   Status ReadbackEN
Set Status Readback Location Type Command 
The Set Location Type command sets the status location type to the 
specified value. Location type is used in conjunction with the location 
unit to identify an entity location for a status request (Inquire Status 
Readback Entity command).
E
C * s # T 
# =0- Invalid location
1 - Currently selected
2 - All Locations
3 - Internal
4 - Downloaded Entity
5 - Cartridge
7 - User-installable ROM device (SIMMs)
Default =0
Range =0 - 5, 7
If a value outside the range is received, the location type is set to 0.
When the location type is 0 and an Inquire Entity command is 
received, an error response is generated (refer to the “Status 
Response Error Codes” section later in this section for additional 
information).
A printer reset returns the location type setting to 0.
The printer retains the location type setting. If the Set Status 
Readback Location Type command is not sent to change the setting 
for an entity request, then the existing location type setting is used.