PC104 View Datasheet(PDF) - PMD
Part Name
Description
MFG CO.
'PC104' PDF : 70 Pages View PDF
2
Operation
2.3.3 DAC Output Enable
In addition to the amplifier enable outputs described above, there is a dedicated card function which
allows the DAC output signals to be shunted to 0 volts for safety purposes (DAC disabled) or
allowed to be set by the motion processor (DAC enabled). This ‘shunting’ occurs at a hardware level
outside the motion processor itself, and represents an additional safety layer to control the motor
command.
ReadIO and WriteIO commands
The status of the DAC output enable function can be read using the ReadIO command, and the DAC
output enable status can be set using the WriteIO command, with an I/O address of +1. See the table in
section 2.3.2 on the previous page for a summary of the bit functions for I/O address word +1.
To read the status of the DAC output enable function, ReadIO is used with address +1. The value
currently in use will appear in bit 7. A 1 value indicates DAC output is enabled, which means the
voltage being output by the DACs is programmed by the motion processor, while a 0 value indicates
it is disabled, which means the voltage being output by the DAC is forced to 0.0 volts.
To enable or disable the DAC enable function, the WriteIO command is used with an address of +1.
The change mask bit at bit 15 must be loaded with a 1, and bit 8 must be loaded with the desired
value of 0 to disable, and 1 to enable output.
The default value, upon powerup, for DAC Output Enable is disabled. In addition, the DAC Output
Enable is disabled upon a hard reset, which is a reset via the PCI bus, or via the external Reset signal. See
section 2.3.7, Reset, page 29, for more information.
Since, for safety reasons, the default condition of the DAC Output is disabled, the DAC Output
must be enabled by the user for proper DAC-based operation to occur.
Example
To set the DAC output enable function to enabled, the C-Motion command
PMDWriteIO(axis_handle, +1, 0x8080) is used. To disable the DAC output the command
PMDWriteIO(axis_handle, +1, 0x8000) is used.
C-Motion commands
In addition to accessing these signals using the C-Motion commands PMDReadIO and PMDWriteIO,
you can use card-specific C-Motion functions for this purpose. The available card specific functions for
this feature are:
C-Motion command
PMDMBSetDACOutputEnable
PMDMBGetDACOutputEnable
Arguments
axis handle,
write_value
axis_handle,
read_value
Function description
This function sets the DACOutputEnable
status. A 1 value written enables DAC
output, while a 0 disables it.
This function reads the value of the
DACOutputEnable function. A 1 indicates
enabled, a 0 indicates not enabled.
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Navigator-PC/104 User’s Guide
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