Campbell CR510 Manual do Operador descarregar pdf (Página 233)

TD ADDENDUM—SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

AD-8-5

8.4 INTERRUPT SUBROUTINE USED

TO COUNT SWITCH CLOSURES

(RAIN GAGE)

Subroutines given the label of 97 or 98 will be

executed when control ports 7 or 8,

respectively, go high (5 V, see Instruction 85,

Section 12). In this example, Subroutine 98 and

control port 8 are substituted for a pulse

counting channel to count switch closures on a

tipping bucket rain gage.

The subroutine adds 0.254 (mm, bucket

c

alibrated for 0.01 inch tip) to an input location

and uses Instruction 22 to delay 0.2 seconds.

The delay is to insure that any switch bouncing

(

when closing, the contacts actually bounce off

each other, making and breaking the circuit

several times) has died out before the

subroutine is completed. (The pulse count

inputs do this automatically.) Without the delay,

the subroutine could be completed and called

again by a bounce, causing false counts. The

interrupt has no effect while the subroutine is

still being executed.

Subroutine 98 is in effect keeping a running

total in Input Stor

age. On the output interval,

this total is sampled to Final Storage and

zeroed by the program in Program Table 1.

To provide comparison, this example has the 2

puls

e inputs also reading rain gages. (In a real

situation, it is more likely that the pulse counters

would be used for 2 wind speeds.) In Program

Table 1, the 2 normal pulse inputs are read and

the hourly totals output to Final Storage with

Instruction 72.

The rain gage is connected as diagrammed

below

. When the switch closes, 5 volts is

applied to port 8 which causes the subroutine to

be executed.

FIGURE 8.4-1. Connections for Rain Gage

Input location Assignments:

10:Rain_1 (from Pulse count)

11:Rain_2 (from Pulse count)

12:Rain_3 (from subroutine 98 while

O

utput Flag is low)

* 1 Table 1 Programs

01: 10 Sec. Execution Interval

01: P3 Pulse

01: 2 Reps

02: 1 Pulse Input Chan

03: 2 Switch closure

04: 10 Loc [:Rain_1 ]

05: .254 Mult

06: 0 Offset

02: P84 Data Table

01: 0 Seconds into interval

02: 3600 Seconds interval

03: 0 Records (0=auto; -=redirect)

03: P72 Totalize

01: 2 Reps

02: 10 Loc Rain_1

04: P70 Sample

01: 1 Reps

02: 12 Loc Rain_3

05: P92 If time is

01: 0 seconds into a

02: 3600 second interval

03: 30 Then Do

06: P30 Z=F

01: 0 F

02: 0 Exponent of 10

03: 12 Z Loc [:Rain_3 ]

07: P95 End

08: P End Table 1

* 3 Table 3 Subroutines

01: P85 Beginning of Subroutine

01: 98 Subroutine Number

02: P 34 Z=X+F

01: 12 X Loc Rain_3

02: .254 F

03: 12 Z Loc [:Rain_3 ]

03: P22 Excitation with Delay

01: 1 EX Chan

02: 0 Delay w/EX (units=.01sec)

03: 20 Delay after EX (units=.01sec)

04: 0 mV Excitation

04: P95 End

05: P End Table 3

1 2 ... 228 229 230 231 232 233 234 235 236 237 238 ... 263 264

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