Endress+Hauser Fieldgate FXA42, Руководство по эксплуатации

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Fieldgate FXA42 Operation
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Internally, the inputs/outputs are addressed via an interface index, device index, value
index and, optionally, an array index. If the Fieldgate FXA42 has a number of digital
inputs/outputs and a Modbus master interface, for example, the interface index will select
one of these two interfaces. The device index can select the Modbus slave, for example,
and the value index would therefore select the relevant Modbus register. The array index is
also used if the corresponding value addresses an element of an array.
When you hover the cursor over an I/O element, a tool tip appears displaying the indexes,
data type and array size.
Variables
The Variable element represents variables that are not linked to a physical I/O. A Variable
element corresponds to a variable with the same name and can be used as either an input
or an output. Variables can be configured on the Variable page.
Unit Description
Variable
A0034323
This element represents the value of the variable during the input stage of the IPO cycle.
Variable
A0034324
This element represents a variable as an output. It writes its value to the variable during the
output phase of the IPO cycle.
Constants
If you add a constant via the toolbar, a dialog box opens which you can use to enter a fixed
value. This value can be a decimal integer, a floating point or a string value. Integer values
are limited to the range [-2 31 , 2 32 -1]. Floating point values are limited to an accuracy of 15
decimal places. Strings are limited to 4096 bytes.
The data type of a constant is the smallest data type that can represent the value of the
constant. Here are some examples:
• 0 → Boolean (false)
• 1 → Boolean (true)
• 120 → 8-bit unsigned integer
• -5 → 8-bit signed integer
• 500 → 16-bit unsigned integer
• -200 → 16-bit signed integer
• 70000 → 32-bit unsigned integer
• -35000 → 32-bit signed integer
• 1.5 → 32-bit floating point number
• 3.14159265359 → 64-bit floating point number
• 5m → String
Constants are processed in the input stage of the IPO cycle.
The value of the constant can be changed. To change the value of the constant, right-click
the element. A popup menu appears (see the following graphic). Select the entry Change
value .