Automated Logic G4106 Technische instructies - Pagina 7

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Custom Translation Tables

In addition to the inputs already mentioned, it is possible

to create translation tables for non-standard thermistor or

slidepot inputs. Provided on the parameter page of the

G4106 module driver (see Figure 14) are two user

definable tables for translating these inputs.

The following are typical applications for the custom

translation tables:

•

Thermistors other than Type 2 (such as Type 3).

•

Slide potentiometer inputs.

•

Non-linear voltage inputs. (0-5 VDC maximum

range)

These tables use a 10 point linear translation method to

approximate a non-linear curve of resistance or voltage to

the desired units.

Procedure

Display the G4106 module driver parameter page (FB

#15) in SuperVision.

For thermistor, slidepot, and other resistance inputs

set the option "Is input specified in voltage?" to NO.

For voltage inputs, set the option to YES.

Determine the accuracy and range needed. Note the

following:

•

Values which lie between two defined entries are

interpolated linearly by the FB.

•

The first and last entries of the resistance table

should always be set to zero and infinity (32767x

10 represents infinity) in the event that the sensor

should short or open. In the case of voltage

inputs, the first and last input voltages should be

set to zero and 5 V. These are the default values.

Determine the resistance or voltage at the desired

settings. This information may be obtained either

from manufacturer reference tables or through testing.

Select a custom translation table that is not currently

in use. Record the custom gain from this table for use

when defining inputs which will reference this custom

translation table in the module.

Enter the scaled voltage or resistance input on the left

and then enter the corresponding value on the right

(see Figures 7 and 8 for examples).

Rev (29-AUG-97) • Module Driver v4.7

The resistance values of the slidepot in Figure 8 (left

column) were obtained by measuring the resistance

of the positions of the slidepot in 1/8 increments (far

left, 1/8, 1/4, 3/8... far right).

NOTE: The lowest resistance range allowed on a

slidepot input is 5k Ohms. This guarantees that sufficient

resistance exists between steps to allow for good linear

approximation.

Note that the slidepot input values (see Figure 9,

right column) are defined with a setpoint-bias rather

than absolute temperatures. The GFB can be

designed to multiply these input values by a user-

definable parameter as the slidepot is adjusted and

then add the result to the zone setpoint. This method

allows you to globally modify the above parameter

for all function blocks in the module instead of

changing the lookup table parameters for each zone.

Download parameters to this FB.

To activate these tables enter the gain of the

translation table used (either 15.00 or 15.06) on the

FB parameter pages that contain the input for which

the table applies. Set the offset to 0.00.

Input Ohms

x 10

230

x 10

405

x 10

752

x 10

935

x 10

1172

x 10

1478

x 10

1879

x 10

2406

x 10

7032

x 10

32767

x 10

Figure 7: Example Custom Table for a Precon Type 3

Thermistor Sensor

Input Value

Ohms

300

150

120

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