Siemens SIMATIC NET Spezifikationen PDF herunterladen (Seite 16)

6 Siemens Simatic S7 Driver Online Help

See Also

Understanding Device Timing Properties: Reply Timeout, Retry, and Delay Time

What is Signal Conditioning?

Signal conditioning is a method of scaling raw data into a range that is meaningful to

your operators. For example, a 4 to 20 milliampere sensor that returns a value of 819

to 4095 is typically meaningless to operators. However, scaling the value to a

percentage or a milliampere range is much more useful.

You can select the type of signal conditioning to use when you configure a database

block. Once specified, the driver scales (converts) the data to a value within the

specified range.

Example

Suppose you want to scale a pressure to a percentage. The pressure ranges from 0 to 500

pounds per square inch (psi). These values are transmitted as voltage ranging from 0 to 10 and

then digitized to a range of 0 to 4095.

To scale the pressure, you select the following values in your database block:

• Signal conditioning: 12BN (12-bit binary)

• EGU range: 0 to 100

12BN is selected because this type of signal conditioning accepts values in the range of 0 to

4095. By matching the range of values in the process hardware, you ensure the driver can

properly convert the raw data values to the database block’s EGU range. By entering a range

of 0 to 100, you ensure the driver scales the incoming value to a percentage you can display.

If you select a type of signal conditioning that does not have the same range of values as your

process hardware, the driver erroneously scales the data. For example, if you select 8BN,

values over 255 are scaled incorrectly because the most significant bit is ignored.

Consequently, a value of 256 is treated as 0.

However, you can always select no signal conditioning. This option lets you display the raw

values to your operators. To use this feature, the database block’s EGU range must match the

incoming range of values in the process hardware, which is 0 to 4095 in this example.

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Siemens SIMATIC NET Spezifikationen Seite 16