CALCulate:COMPare:MASK[:<width>]

Syntax | Description | Parameters | Remarks | Return Format | Examples

Syntax

CALCulate:COMPare:MASK[:<width>] <data>, (@<ch_list>)

CALCulate:COMPare:MASK? (@<ch_list>)

Description

This command is used in conjunction with the CALCulate:COMPare:DATA command to set the digital mask data for pattern comparisons on the specified digital input channels. You can use the pattern comparison feature to generate an alarm or hardware interrupt condition (34950A only) when a specific digital pattern is detected. Pattern comparisons always start on the lowest-numbered channel in the bank and extend to all channels involved in the channel width (see CONFigure:DIGital:WIDTh command).

Used With:

• 34950A Digital I/O Module (digital input channels only)

• 34952A Multifunction Module (digital input channels only)

Parameters

Remarks

• Depending on the width specified, the channel numbering is modified as shown below. For example, if you specify the width as a 16-bit WORD on the 34950A, channels 101 and 102 are combined and addressed collectively as channel 101.  

  34950A	Bank 2				Bank 1
  BYTE (8 Bits):	Ch 204	Ch 203	Ch 202	Ch 201	Ch 104	Ch 103	Ch 102	Ch 101
  WORD (16 Bits):	Ch 203		Ch 201		Ch 103		Ch 101
  LWORd (32 Bits):	Ch 201				Ch 101
  34952A	Bank 1
  BYTE (8 Bits):	Ch 4	Ch 3	Ch 2	Ch1
  WORD (16 Bits):	Ch 3		Ch 1
  LWORd (32 Bits):	Ch 1

• The channel width takes precedence over the specified digital pattern. If the specified pattern is greater than the channel width, additional bits will be ignored. For example, if you set the channel width to "BYTE" and then specify a pattern of "256" (1 0000 0000), the pattern will be truncated to "0000 0000" (the leading "1" will be ignored).

• Pattern comparisons are performed on a per-bank basis (i.e., the entire bank is reserved for the pattern comparison). For example, if you are using channels 101 and 102 for pattern comparison (assumes 34950A) and then perform a static read of channel 103, the module will perform a pattern comparison on channels 101 and 102.

• After specifying the desired digital pattern and mask, use the CALCulate:COMPare:STATe command to enable pattern comparisons on the specified channels.

• For the 34950A only, pattern comparisons can be performed with or without handshaking (see CONFigure:DIGital:HANDshake command). If you are using handshaking, the specified digital pattern is evaluated with each handshaking operation. If you are not using handshaking, the specified digital pattern is evaluated continuously as soon as you enable the pattern comparison mode.

• For the 34950A only, hardware interrupts are reported on the INTR line (one line is available per bank). See the [SENSe:]DIGital:INTerrupt[:ENABle] command to enable interrupts to be reported.

• A Factory Reset (*RST command) clears the mask and turns off the pattern comparison mode. An Instrument Preset (SYSTem:PRESet command) or Card Reset (SYSTem:CPON command) does not clear the mask and does not turn off the pattern comparison mode.

Return Format

The query command returns the mask as a decimal value (binary and hexadecimal values are converted to their decimal equivalents). Multiple responses are separated by commas.  

Examples

The following program segment sets the digital pattern for the 34950A in slot 3, applies a mask to the upper four bits, and then enables the pattern comparison mode. When the data read from the upper four bits is equal to the comparison pattern, a hardware interrupt will be generated. In this example, handshaking is not used.

CALC:COMP:DATA:BYTE 140,(@3101)  !Set comparison pattern (1000 1100)
CALC:COMP:MASK 240,(@3101)  !Set mask pattern (1111 0000)
DIG:INT:MODE COMPARE,(@3101)  !Interrupt on pattern match
DIG:INT:ENAB ON,(@3101)  !Enables interrupts on channel 101
CALC:COMP:STAT ON,(@3101)  !Enable pattern comparison mode

To illustrate how the calculations are performed, see the example below which assumes that a decimal 146 was read from the channel. Since the calculations produce a non-zero result (decimal 16), an interrupt is not generated.

The following query returns the comparison pattern selected for the 34950A in slot 3.

CALC:COMP:MASK? (@3101)  !Always returns decimal equivalent

Typical Response:  240

The following program segment sets the digital pattern for the 34952A in slot 5, applies a mask to the lower byte, and then enables the pattern comparison mode. When the data read from the lower byte is equal to the comparison pattern, an alarm will be generated on Alarm 2.

CALC:COMP:DATA:WORD #HF6F6,(@5001)  !Set comparison pattern (1111 0110 1111 0110)
CALC:COMP:MASK #H00FF,(@5001)  !Set mask pattern (0000 0000 1111 1111)
CALC:COMP:TYPE EQUAL,(@5001)  !Generate alarm on pattern match
OUTP:ALARM2:SOUR (@5001)  !Enable alarms
CALC:COMP:STAT ON,(@5001)  !Enable pattern comparison mode

To illustrate how the calculations are performed, see the example below which assumes that a decimal 37595 was read from the channel. Since the calculations produce a non-zero result (decimal 13), an alarm is not generated.

The following query returns the comparison pattern selected for the 34952A in slot 5.

CALC:COMP:MASK? (@5001)  !Always returns decimal equivalent

Typical Response:  255

See Also

CALCulate:COMPare:DATA

CALCulate:COMPare:STATe

CALCulate:COMPare:TYPE

CONFigure:DIGital:HANDshake

OUTPut:ALARm<n>:SOURce

[SENSe:]DIGital:INTerrupt[:ENABle]