VXI VT1422A - Manual (Page 121)

Programming the VT1422A for Data Acquisition and Control 119 Chapter 4
Frequency Function
The frequency function uses two commands. For more on this VT1534A and
VT1538A capability, see the appropriate SCP’s User’s Manual.
To set the frequency counting gate time execute
[SENSe:]FREQuency:APERture <gate_time>,(@<ch_list>)
To set the digital channel function to frequency
[SENSe:]FUNCtion:FREQuency (@<ch_list>)
Totalizer Function
The totalizer function uses two commands also. One sets the channel function
and the other sets the condition that will reset the totalizer count to zero.
For more on this VT1534A and VT1538A capability see the appropriate
SCP’s User’s Manual.
To set the VT1534A’s totalize reset mode
[SENSe:]TOTalize:RESet:MODE INIT | TRIG,(@<ch_list>)
To configure VT1534A channels to the totalizer function
[SENSe:]FUNCtion:TOTalize (@<ch_list>)
Setting Up Digital
Outputs
Digital outputs can be configured for polarity, output drive type and, depending
on the SCP model, a selection of output functions as well. The following
discussion will explain which functions are available with a particular
Digital I/O SCP model. Setting a digital channel’s output function is what
defines it as an output channel.
Setting Output Polarity
To specify the output polarity (logical sense) for digital channels use the
command OUTPut:POLarity <mode>,(@<ch_list>). This capability is
available on all digital SCP models. This setting is valid even while the specified
channel in not an output channel. If and when the channel is configured for
output (an output FUNCtion command), the setting will be in effect.
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The <mode> parameter can be either NORMal or INVerted. When set
to NORM, an output channel set to logic 0 will output a TTL
compatible low. When set to INV, an output channel set to logic 0 will
output a TTL compatible high.
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The <ch_list> parameter specifies the channels to configure.
The VT1533A has 2 channels of 8 bits each. All 8 bits in a channel
take on the configuration specified for the channel. The VT1534A and
VT1538A have 8 I/O bits that are individually configured as channels.
To configure the higher 8 bit channel of a VT1533A for inverted polarity:
OUTP:POLARITY INV,(@109)
SCP in SCP position 1
To configure the upper 4 bits of a VT1534A for inverted polarity:
OUTP:POL INV,(@132:135)
SCP in SCP position 4