Automated Logic R683 Technical Instructions - Page 10

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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

R683 module driver (see Parameter Page) 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 R683 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 14 and 15 for examples).

Rev. (30-JAN-98) • RLM v4.7

The resistance values of the slidepot in Figure 15

(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 that the slidepot input values (see Figure 15,

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.

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 14: Example Custom Table for a

Precon Type 3 Thermistor Sensor

Input Ohms

x 10

474

x 10

607

x 10

910

x 10

1210

x 10

1540

x 10

1860

x 10

2150

x 10

2360

x 10

2400

x 10

32767

x 10

Figure 15: Example Custom Table for a Sample

(Tested Resistance Entered on the Left)

Input Value

Ohms

Input Value

Ohms

Slidepot

300

150

120

-60.8

-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00