Accessing Cards

The VISA resource name supplied to pipx40_init specifies the Pickering card to be opened. A typical example might be "PXI0::15::INSTR", which targets the card at the logical location PXI bus = 0, slot = 15. The VISA environment commonly allows the setting up of aliases, so that for example the name "SWITCH_CARD" can be assigned to represent "PXI0::15::INSTR". A program can then open the card using the resource name "SWITCH_CARD" and if the card's location is changed subsequently it is only necessary to alter the alias, instead of editing the program.

When a card is successfully opened by pipx40_init, VISA returns an Instrument handle associated with the card. This handle is then used as necessary to specify the card in other function calls.

Pickering PXI cards contain one or more independently addressable functional blocks, or sub-units. Sub-unit numbers begin at 1, and separate sequences are used for input and output functions. This number is used in function calls to access the appropriate block. Generally, sub-unit numbers correspond directly to the bank numbers specified in hardware documentation.

Model	Configuration	INPUT sub-unit #1	OUTPUT sub-unit #1	OUTPUT sub-unit #2	OUTPUT sub-unit #3
40-110-021	16 SPDT switches	None	16 SPDT switches	None	None
40-290-121	Dual Programmable resistors + 16 SPDT switches	None	Resistor #1	Resistor #2	16 SPDT switches
40-490-001	Digital I/O	16-channel inputs	32-channel outputs	None	None
40-511-021	Dual 12 x 4 matrix	None	12 x 4 matrix #1	12 x 4 matrix #2	None

The numbers of input and output sub-units in a card can be obtained using function pipx40_getSubCounts.

pipx40_getSubType type desc.	pipx40_getSubInfo type value	Characteristics
INPUT	1	Digital inputs.
SWITCH	1 - pipx40_TYPE_SW	Uncommitted switches. Switches can be selected in any arbitrary pattern.
MUX	2 - pipx40_TYPE_MUX	Multiplexer, single channel. Only one channel can be selected at any time.
MUXM	3 - pipx40_TYPE_MUXM	Multiplexer, multi channel. Any number of channels can be selected simultaneously.
MATRIX	4 - pipx40_TYPE_MAT	Matrix, LF. Multiple crosspoints may be closed on any row or column, though there may be a limit on the total number that can be closed simultaneously. Some matrices intended for RF use are also characterised as this type, though closure of multiple crosspoints on a row or column will inevitably compromise RF performance.
MATRIXR	5 - pipx40_TYPE_MATR	Matrix, RF. A matrix intended for RF use, generally permitting the closure of only one crosspoint on each row and column.
DIGITAL	6 - pipx40_TYPE_DIG	Digital outputs. Outputs can be energised in any arbitrary pattern.
RES	7 - pipx40_TYPE_RES	Programmable resistor.
ATTEN	8 - pipx40_TYPE_ATTEN	Programmable RF attenuator.
PSUDC	9 - pipx40_TYPE_PSUDC	DC power supply.