National Instruments 321645c-01 用户手册

Chapter 2

Function Reference — GPCTR_Change_Parameter

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Legal values for paramValue depend on paramID. The following paragraphs list legal 
values for paramID with explanations and corresponding legal values for paramValue:

ND_SOURCE

The general-purpose counter counts transitions of this signal. Corresponding legal values for 
paramValue are as follows:

Table 2-20.  Legal Values for gpctrNum Parameter

ND_COUNTER_0

ND_COUNTER_1

ND_COUNTER_0

ND_COUNTER_1

ND_COUNTER_2

ND_COUNTER_3

ND_COUNTER_4

ND_COUNTER_5

ND_COUNTER_6

ND_COUNTER_7

Table 2-21.  Legal Values for paramValue when paramID =

 ND_SOURCE

ND_PFI_0

 through 

ND_PFI_9

—

the 10 

I/O connector pins*.

ND_RTSI_0

 through 

ND_RTSI_6

—the 

seven RTSI lines.

ND_INTERAL_20_MHZ

 and 

ND_INTERNAL_100_KHZ

—the internal 

timebases

ND_OTHER_GPCTR_TC

—the terminal 

count of the other general-purpose 
counter (See Table 2-22 for definition of 
other counter).

I/O connector pins 

ND_PFI_39*

,

ND_PFI_35*

, 

ND_PFI_31

,

ND_PFI_27

, 

ND_PFI_23

,

ND_PFI_19

, 

ND_PFI_15

, and 

ND_PFI_11

.

ND_RTSI_0

 through 

ND_RTSI_6

—the seven RTSI 

lines.

ND_INTERNAL_20_MHZ

 

and

 

ND_INTERNAL_100_HZ

—the internal timebases.

ND_INTERNAL_MAX_TIMEBASE

—the maximum 

timebase. The value of this timebase can be determined 
by a 

GPCTR_Watch

 call, 

ND_OTHER_GPCTR_GATE

 

(See Table 2-22 for definition of other counter).

ND_OTHER_GPCTR_TC

—the terminal count of the 

other general-purpose counter (See Table 2-22 for 
definition of other counter).

*ND_PFI_39

, 

ND_PFI_35

, 

ND_COUNTER_2 

through 

ND_COUNTER_7

 are not available on 455X 

devices.