SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES

8.6SDM-A04 ANALOG OUTPUT MULTIPLEXER TO STRIP CHART

This example illustrates the use of the SDM- A04 4 Channel Analog Output Multiplexer to output 4 analog voltages to a strip chart.

While of questionable value because of current requirements and strip chart reliability, some archaic regulations require strip chart backup on weather data. The SDM-A04 may be used with the CR10 to provide analog outputs to strip charts. The output values in this example are wind speed, wind direction, air temperature, and solar radiation.

Instruction 103 is used to activate the SDM- A04. The (4) millivolt values to output must be stored in adjacent Input Storage locations, the first of which is referenced in Instruction 103.

The following program measures the sensors every 5 seconds. The readings are moved to another 4 locations and scaled to a 0 to 1000 millivolt output for the SDM-A04. Wind direction is changed from a 0-360 degree input to output representing 0 to 540 degrees. This conversion is done in a subroutine which is described in the next example.

The example also includes instructions to output wind vector and average temperature and solar radiation every hour.

Input Location Labels:

1:WS 2:0-360 WD 3:Ta 4:SR 5:WS output 6:0-540 out 7:Ta output 8:SR output 10:0-540 WD

*1 Table 1 Programs

01:

5

Sec. Execution Interval

01:

P3

Pulse

01:

1

Rep

02:1 Pulse Input Chan

03:

22

Switch Closure

04:

1

Loc [:WS

]

05:

1.789

Mult

 

06:

1

Offset

 

02:

P4

Excite,Delay,Volt(SE)

01:

1

Rep

02:14 250 mV fast Range

03:

1

IN Chan

04:1 Excite all reps w/EXchan 1

05:

5

Delay (units .01sec)

06:

1000

mV Excitation

07:2 Loc [:0-360 WD ]

08:.7273 Mult

09:

0

Offset

03:P11 Temp 107 Probe

01:

1

Rep

02:

2

IN Chan

03:2 Excite all reps w/EXchan 2

04:

3

Loc [:Ta

]

05:

1.8

Mult

 

06:

32

Offset

 

04:

P1

Volt (SE)

 

01:

1

Rep

 

02:2 7.5 mV slow Range

03:

3

IN Chan

 

04:

4

Loc [:SR

]

05:.14493 Mult

06:

0

Offset

05:

P92

If time is

01:

0

minutes into a

02:

60

minute interval

03:

10

Set high Flag 0 (output)

06:

P54

Block Move

01:4 No. of Values

02:1 First Source Loc WS

03:

1

Source Step

04:

5

First Dest. Loc [:WS output]

05:

1

Destination Step

07:

P86

Do

01:1 Call Subroutine 1

08:P53 Scaling Array (A*loc +B)

01:

5

Start Loc [:WS output]

02:10 A1 SCALE WS,

0-100 MPH = 0-1000 MV

03:

0

B1

04:1.8519 A2 SCALE WD,

 

 

0-540 DEG = 0-1000 MV

05:

0

B2

06:5.7143 A3 SCALE TEMP,

 

 

-25 - 100 F =0-1000 MV

07:

25

B3

08:

1000

A4 SCALE RADIATION,

 

 

0-1KW/M^2 = 0-1000 MV

09:

0

B4

8-7