VTI Instruments EX1000A, Руководство пользователя

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VTI Instruments Corp.
106 EX10xxA Programming
The vtex10xxA_set_dio_pulse function is used to generate a 1

s pulse on selected channels of the
digital I/O port. The pulse will occur only if the selected channels are enabled as outputs. When a
channel is programmed with a static level of high, the pulse will be low-going. When a channel is
programmed with a static level of low, the pulse will be high-going. Each pulse generation requires
a separate function. This function accepts a value that represents the channels to be pulsed within
the 8-bit port, specified in either decimal (0 through 255) or hex (0x00 through 0xFF). Within the
8-bit field, the MSB corresponds to DIO channel 7, and the LSB corresponds to DIO channel 0.
Example: This code block sets bit 7 to a static level of low and then generates a high-going pulse.
vtex10xxA_set_dio_output(vi, 0x00);
vtex10xxA_set_dio_output_enable(vi, 0x80);
vtex10xxA_set_dio_pulse(vi, 0x80);
Configure DIO Limit Events
In addition to performing simple input and output operations, the digital I/O port can also be linked
to reflect the state of input channel limit evaluations. This linkage is termed a DIO limit event. DIO
limit events are programmable on a per channel basis; that is, each of the 8 DIO channels can be
configured with a unique set of operational characteristics. In nominal operation, a DIO channel that
is linked to an input channel’s limit evaluation will transition from low to high whenever the limit
is exceeded.
The linkage of a DIO channel to a specific limit condition on a specific input channel is
accomplished with the vtex10xxA_set_dio_limit_event function. Multiple linkages per DIO channel
are allowed and are logically OR’ed together. That is, a DIO channel that is linked to four input
channel limit evaluations will transition whenever any of the four limits are exceeded. Multiple
linkages can be created on the same input channel and/or spanning multiple input channels.
This function accepts the following parameters:

an integer value representing the DIO channel number (0 through 7)

an array of 48 4-bit integer values representing, on a per input channel basis, the linking of
limit evaluations to any of the 4 limit conditions. Within the 4-bit field, the order of the values
is: limit set 0 lower, limit set 0 upper, limit set 1 lower, limit set 1 upper. The values can be
specified in either decimal (0 – 15) or hex (0x00 – 0x0F). Channel 0 through channel 47 are
represented in array elements [0] through [47], respectively.
Example: This code block links DIO channel 7 to set 1 lower limits on input channels 12 and 14
and set 0 upper limit on input channel 1
ViUInt16 limit_masks[48] =
{0,4,0,0,0,0,0,0,0,0,0,0,2,0,2,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
vtex10xxA_set_dio_limit_event(vi, 7, limit_masks);
The DIO limit event and the scan list configuration controls are autonomous. That is, specifying a
linkage to a specific input channel does not automatically enable it in the scan list. Similarly,
removing an input channel from the scan list does not automatically remove it as a linked limit
condition. DIO limit event linkages to unscanned channels do not cause an error condition and are
simply ignored in the evaluation.