Performance Motion Devices PR8358120, User Manual

Page: 37 / 103

Operation
Prodigy/CME PC/104 User’s Guide
37
2
The eight inputs and eight outputs are read using the Magellan Motion Processor’s ReadIO command and written
using the WriteIO command, with an I/O address of 0. This is illustrated in the following table, along with the bit
locations of the input and output signals.
To read all eight general-purpose digital I/O signals, a ReadIO command is performed at address offset 0. The 16-bit
read word returns the current output values (set using the WriteIO command) in bits 0 - 7, while bits 8 - 15 hold the
digital values corresponding to the signal levels at the connector for those inputs. To write new signal values to the
eight digital outputs, a
WriteIO command to address offset 0 is sent, and the values on bits 0-7 will be output to the
signal connections. The values of bits 8 - 15 are ignored.
Example
To write the value 0xAA to bits 0 - 7, the command WriteIO is used. If the signal pattern 0x55 is present on the eight
input connections, then the command ReadIO 0 will return the value 0x55AA. The upper eight bits reflect the present
value of the input signals, while the lower eight bits reflect the 8-bit value being output.
In addition to the low-level ReadIO and WriteIO commands, the following commands are also supported in C-
Motion and VB-Motion: WriteDigitalOutput , ReadDigitalInput , and ReadDigitalOutput . These commands
provide a clearer and simpler interface to the Prodigy/CME PC/104 card’s general purpose I/O signals by handling
the byte shifting.
2.3.1.1 Connections & associated signals
The general-purpose I/O are direct digital inputs and outputs. There are no associated connections required for these
signals to function properly, however, one or more of the digital grounds must be connected. Digital inputs are pulled
up through 4.7 kOhm resistors to 5V. The power-up default value for all general-purpose digital outputs is low.
See Chapter 4, Electrical Reference , on page 69 for a complete description of the pinout connections to and from the
card.
2.3.2 Amplifier Enable
The signals
AmpEnable 1-4
provide four digital outputs which may be used as amplifier enable signals. They can also be
used as general-purpose digital outputs. They can be read or written using the Prodigy/CME PC/104 card Magellan’s
ReadIO
and
WriteIO
commands.
These outputs are read using the
ReadIO
command, and written to using the
WriteIO
command, using an address
of 1, as shown in the following table:
To read the status of the amplifier enable outputs, the command
ReadIO
is used at address 1. The values currently
being output will appear in bits 0 - 3. To write values to the amplifier enable output signals, the WriteIO command
I/O
Address
Bit
Location Signals
0 0 - 7 DigitalOut0-7
8 - 15 DigitalIn0-7
I/O
Address
Bit
Location Signals
1 0-3 Amplifier enable outputs (0-3)
4-6 Unused
7 DAC enable status (1 = enabled; 0 = disabled)
8-11 Change mask for bits 0-3; amplifier enable outputs (1 = change;
0 = don’t change)
12-14 Unused
15 Change mask for DAC enable (1 = change; 0 = don’t change)