GTCO CalComp BIT PAD TWO DATA User Manual
Bit Pad Two 1
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Operation Overview
Configuration Parameters
Section A: Proximity Transmission
Section B: Remote Control
Section C: Baud Rate
Section D: CTS Handshaking
Section E: Hardware Interface
Connector Pin Assignments
Signal Levels
Section F: Report Format and Cursor Output Codes
Bit Pad Two Packed Binary Format
Bit Pad ASCII BCD Format
Guidelines for Writing a Software Driver
Operating Characteristics and Commands
Section A: Controlling the Report Flow and Content
Primary Modes
Stream Mode, Switch Stream Mode and Report Rate
Point Mode
Remote Request Mode
Modifiers
Absolute Mode
Relative Mode
Increment Mode
Section B: Combining Characteristics
Section C: Other Commands
Resolution Send Configuration
Transmission Control
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Table of Contents
Bit Pad Two 2
Chapter 5
Chapter 6
Appendix A
Appendix B
Appendix C
Appendix D
Reset
NOP (No Operation)
Checking the Data Tablet
Section A: Self-Test Diagnostic Function
Section B: In Case of Failure
Operating Environment, Installation, Care and Service
Section A: Operating Environment
Temperature and Humidity
Power
Section B: Unpacking and Installation
Unpacking
Installation
Changing the Stylus Refill
Section C: FCC Considerations
Section D: Care and Cleaning
Section E: Service
Specifications
Physical Description
Power Requirements
Optional Power Supplies
Material and Cosmetics
Operating Specifications
ASCII Conversion Chart
How the Bit Pad Two is Different from Bit Pad One
Quick Reference Sheet of Commands and Switch Settings
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Bit Pad Two 3
Chapter 1: Operation Overview
The Bit Pad Two is a data tablet that acts as an input device. It allows for the translation of
graphic information into digital, suitable for a digital device such as a computer.
The Bit Pad Two is valuable in many applications, including:
Steering a cursor on a computer terminal.
Picking locations on a menu
Digitizing maps, drawings, etc.
The parts of a standard Bit Pad Two are the tablet, cursor or stylus, data/power cable and
power supply.
Tablet: Table-like surface. The tablet can tilt or lie flat.
Cursor: Handheld device that’s used with the tablet to locate points. A cursor has a
crosshair for precisely sighting the points. They are available with three or four buttons.
Stylus: Pen-like, handheld device. Use it with the tablet to locate points. The stylus has
two buttons; one on the outside of the barrel and another inside the barrel, activated by
pressing the refill tip. Refills are available in marking and non-marking,
Data/Power Cable: Cable and connector assembly that interfaces the data tablet to the
host and power supply.
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Power Supply: Source of power for the Bit Pad Two. It attaches to the data/power cable
and the power line.
Adapter Cables: Cable assemblies that can change the gender of the data/power cable
connector; reverse the communication lines or convert the power supply plug to the
international standards.
The Bit Pad Two translates the position of the stylus or cursor on the tablet into digital
information and communicates it to the host. The host is represented by a computer. The
stylus or cursor position is expressed as an X, Y coordinate pair. One coordinate pair is
called a report. Reports can only be collected when the stylus or cursor is in the tablet’s
active area and is in proximity.
Proximity is the maximum distance above the active area that the cursor or stylus can be
held and report a valid position. This, in effect, establishes a three-dimensional volume,
within which the cursor or stylus can issue valid reports. Reports issued from outside of
this volume are out of proximity (out-of-prox) and therefore, do not represent the current
position of the stylus or cursor.
Bit Pad Two 5
Reports are in counts of resolution, expressed as absolute coordinates or relative
coordinates.
Resolution: Smallest distance or movement that the data tablet can distinguish.
Resolution is a measure of precision and is expressed in lines per inch (lpi) or lines per
millimeter (lpmm).
Counts of Resolution: Unit of measure: one count is the distance between two lines of
resolution.
Absolute coordinates are measured from the tablet’s origin (0, 0). Relative coordinates are
measured relative to the last report location. Reports are in absolute coordinates when the
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data tablet is in Absolute Mode. Reports are in relative coordinates when the data tablet is
in Relative Mode.
Absolute and Relative modes are two of the Bit Pad Two’s many operating characteristics.
Other operating characteristics govern when reports are issued; how fast they are issued
and the tablet resolution.
The operating characteristics can be set by commands from the host or by switches. The
switches, slide or rocker, are grouped in banks of eight per DIP switch. The DIP switches
are located on the printed circuit board inside the tablet.
Also, established by switch are the data tablet’s configuration parameters. These
parameters specify the data communications, such as CTS handshaking and baud rate, and
the data format.
Chapter 2: Configuration Parameters
For successful communication between a Bit Pad Two and its host, the hardware interface
and configuration parameters must be compatible. The hardware interface is RS-232C.
The configuration parameters are:
Proximity transmission
Remote control
Baud rate
CTS handshaking
Report format and cursor output codes
This chapter describes the alternatives available for each of the configuration parameters.
The parameters are switch-selective. Appendix D Quick Reference Sheet of Commands and
Switch Settings summarize the switch settings and defaults that the factory normally uses.
Section A: Proximity Transmission
The data tablet can be configured to:
Transmit reports only when the cursor or stylus is in proximity.
Transmit reports regardless of whether the cursor or stylus is in or out of proximity.
If the data tablet is configured the second way, reports issued from out-of-prox will reflect
that state with a special bit or character. Reports in the binary format have a bit assigned
Bit Pad Two 7
to report the proximity status. Reports in the ASCII BCD format use the cursor/stylus flag
character to identify an out-of-prox report.
Section B: Remote Control
The data tablet can be configured to accept or reject commands from the host. When the
remote control is enabled, the data tablet is receptive to commands from the host.
When the remote control is disabled, the data tablet only responds to the following
commands:
Section C: Baud Rate
Baud rate is the number of bits transmitted each second between host and peripheral (Bit
Pad Two) or peripheral and host. The available baud rates are 110, 150, 300, 1200, 2400,
4800, 9600 and 19200.
Section D: CTS Handshaking
The Bit Pad Two supports CTS (Clear to Send) handshaking, hardware governed method of
communications control. The Bit Pad Two is configured as a DTE (Data Terminal
Equipment). Therefore, RTS (Request to Send) and DTR (Data Terminal Ready) are always
asserted.
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If the switch is set to enable CTS handshaking, the data tablet awaits CTS from the host
before it can issue reports. If CTS is not asserted, the data tablet is inhibited from sending
reports. If the switch is set to disable CTS handshaking, the data tablet ignores the CTS line.
Section E: Hardware Interface
The Bit Pad Two has an RS-232C interface. It is full duplex, asynchronous and serial. View
the sections below for the pin assignments and signal levels.
Connector Pin Assignments
The data/power cable is a single, shielded cable terminated with a 25-pin female D
connector and a 4-pin male in-line connector. The D connector plugs into the host and the
in-line connector attaches into the power supply. The pin assignments appear below:
RS-232C Data/Power Cable – Pin Assignments for the 25-Pin D Connector
RS-232C Data/Power Cable – Pin Assignments for the 4-Pin In-Line Connector
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An adapter cable is available to change the connector gender from female to male. Also, a
reversing cable is available to reverse the communications lines; its pin assignments
appear below:
RS-232C Reversing Cable – Pin Assignments for the 25-Pin D Connector
Signal Levels
The table below specifies the signal levels for data transmissions:
RS-232C Signal Levels
The source of the above tablet is the EIA Standard RS-232C: Interface Between Data
Terminal Equipment and Data Communication Equipment Employing Serial Binary Data
Interchange by the Engineering Department of the Electronic Industries Association
(Washington, D.C.: EIA, 1969).
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Section F: Report Format and Cursor Output Codes
Two report formats are available: packed binary and ASCII BCD.
NOTE: To users of other Summagraphics data tablets or digitizers: the formats described
here are specific to the Bit Pad Two and Bit Pad One. Other Summagraphics products have
similarly named formats, but their content may be different. Regardless of format, reports
are in counts of resolution, not in inches or millimeters.
Within the report format:
You can opt to have parity enabled or not.
If parity is enabled, it can be even or odd.
Select the number of stop bits to be one or two.
You have two cursor output codes to choose from.
The Bit Pad Two is normally configured at the factory in the ASCII BCD report format with
parity enabled (set for even parity), two stop bits and cursor output.
Bit Pad Two Packed Binary Format
The packed binary formats are different for reports issued when the data tablet is in
Absolute Mode vs. Relative Mode. Absolute Mode has 12 bits per coordinate while Relative
Mode has 11 bits and one sign bit per coordinate.
Bit Pad Two Packed Binary Report Format
Bit Pad Two 11
LSB
MSB
PR
F
Least significant bit
Most significant bit
Proximity, 0 when in proximity and 1 when out-of-prox
Flag bit, identifying the stylus or cursor buttons being pressed. The cursor
output codes are switch selective:
*On the 3-button cursor, the buttons are distinguished by raised dimples, rather than by
numbered labels. In the table above, 1 corresponds to one dimple; 2 to two dimples, etc.
Bit Pad Two 12
PH
P
SB
X0 to X11
and
Y0 to Y11
Phasing bit, which is always 1
Parity bit
One or two stop bits
X and Y coordinate bits.
S
X
,
Y
F
Coordinate sign, in Relative Mode only. For a positive coordinate, the character can be
0 through 9. For a negative coordinate, the character is a minus sign (-).
A digit of the X coordinate; each digit is an ASCII character, 0 through 9.
The delineator character, an ASCII comma.
A digit of the Y coordinate; each digit is an ASCII character, 0 through 9.
Flag character identifying the stylus or cursor buttons being pressed. The cursor output
codes are switch-selective:
NOTE: In Relative Mode, X11 and Y11 are the sign bits. The bit is 0 for a positive coordinate
and 1 for a negative coordinate. Furthermore, the remaining bits for a negative coordinate
are in the two’s complement form.
Bit Pad Two ASCII BCD Format
When the data tablet is in Absolute Mode, the ASCII BCD report format is:
XXXX,YYYY, F<CR> or XXXX,YYYY,F<CR><LF>
When the data tablet is in Relative Mode, the ASCII BCD report format is:
SXXX,SYYY,F<CR> or SXXX,SYYYY,F<CR><LF>
As shown in the above formats, the terminator can be a carriage return (<CR>) or a carriage
return and a line feed (<LF>). This is switch-selective.
NOTE: The character 9 is in the cursor/stylus flag position when a report is issued from outof-prox.
Key:
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*On the 3-button cursor, the buttons are distinguished by raised dimples, rather than
by numbered labels. In the table above, 1 corresponds to one dimple, 2 to two dimples
and etc.
<CR>
<LF>
ASCII carriage return
ASCII line feed
Chapter 3: Guidelines for Writing a Software Driver
A computer must have a driver in order for the Bit Pad Two to be connected. The driver is
a software subroutine that collets and decodes Bit Pad Two reports for use by another
(master) program. This section provides some guidelines, in the form of flowcharts, for
writing a driver.
The flowcharts are for a Bit Pad Two using the packed binary report format. The steps are
general for any set of operating characteristics.
NOTE: In the context of these charts, normalize means to combine the two coordinate
bytes into the format required by your master program.
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General Flowchart for Master Program to Read and Process Data Tablet Reports
Bit Pad Two 15
Detail A: Get and Decode Reports Subroutine
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