is dependent upon the sampling interval (e.g., speed, RPM), the value from the excessive interval should be discarded. If the value is discarded the value in the RAM buffer from the previous measurement will be used.

There is also an option to output the count as a frequency (i.e., counts/execution interval in seconds = Hz) as well as discard the result from an excessive interval. This allows the use of a conversion factor that is independent of the execution interval.

The options of discarding counts from long intervals, pulse input type, and using a 16 bit counter are selected by the code entered for the 4th parameter (Table 9-2).

NOTE: All pulse count instructions must be kept in the same table. If the Pulse Count Instruction is contained within a subroutine, that subroutine must be called from Table 2.

TABLE 9-2. Pulse Count ConfigurationCodesCode Configuration

0High frequency pulse

1Low level AC

2Switch closure

3High frequency pulse, sixteen bit counter

4Low level AC, sixteen bit counter

1X Long interval data discarded

2X Long interval data discarded, frequency (Hz) output

PARAM.

DATA

 

NUMBER

TYPE

DESCRIPTION

01:

2

Repetitions

02:

2

Pulse channel number

 

 

for first measurement

03:

2

Configuration code

 

 

(from above table)

04:

4

Input location for first

 

 

measurement

05:

FP

Multiplier

06:

FP

Offset

Input locations altered: 1 per measurement

Intermediate storage locations altered: 1 for each repetition

SECTION 9. INPUT/OUTPUT INSTRUCTIONS

*** 4 EXCITE, DELAY, AND MEASURE ***

FUNCTION

This instruction is used to apply an excitation voltage, delay a specified time, and then make a single-ended voltage measurement. A 1 before the excitation channel number (1X) causes the channel to be incremented with each repetition.

PARAM.

DATA

 

NUMBER

TYPE

DESCRIPTION

01:

2

Repetitions

02:

2

Range code (Table 9-1)

03:

2

Single-ended channel

 

 

number for first

 

 

measurement

04:

2

Excitation channel

 

 

number

05:

4

Delay in hundredths of

 

 

a second

06:

4

Excitation voltage

 

 

(millivolts)

07:

4

Input location number

 

 

for first measurement

08:

FP

Multiplier

09:

FP

Offset

Input locations altered: 1 per measurement

*** 5 AC HALF BRIDGE ***

FUNCTION

This instruction is used to apply an excitation voltage to a half bridge (Figure 13.5-1), make a single-ended voltage measurement of the bridge output, reverse the excitation voltage, then repeat the measurement. The difference between the two measurements is used to calculate the resulting value which is the ratio of the measurement to the excitation voltage. A 1 before the excitation channel number (1X) causes the channel to be incremented with each repetition.

The excitation "on time" for each polarity is exactly the same to insure that ionic sensors do not polarize with repetitive measurements. The range should be selected to be a fast measurement (range 11-15), limiting the excitation on time to less than 800 microseconds at each polarity. A slow integration time should not be used with ionic sensors because of polarization error.

9-3