Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 32)

Analog Outputs
32 Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Absolute (default)
Certain quantities used to drive the analog output are signed, i.e. the quantity can
be both positive and negative. The user has the option of having the absolute
value (value without sign) of these quantities taken before the scaling occurs.
Absolute value is enabled separately for each analog output via the bitmapped
parameter [Anlg Out Absolut].
Important: If absolute value is enabled but the quantity selected for output is
not a signed quantity, then the absolute value operation will have no
effect.
Scaling Blocks
The user defines the scaling for the analog output by entering analog output
voltages into two parameters, [Analog Out1 Lo] and [Analog Out1 Hi]. These
two output voltages correspond to the bottom and top of the possible range
covered by the quantity being output. The output voltage will vary linearly with
the quantity being output. The analog output voltage will not go outside the
range defined by [Analog Out1 Lo] and [Analog Out1 Hi].
Analog Output Configuration Examples
This section gives a few examples of valid analog output configurations and
describes the behavior of the output in each case.
Example 1 -- Unsigned Output Quantity
•
[Analog Out1 Sel] = “Output Current”
•
[Analog Out1 Lo] = 1 volt
•
[Analog Out1 Hi] = 9 volts
Note that analog output value never goes outside the range defined by [Analog
Out1 Lo] and [Analog Out1 Hi]. This is true in all cases, including all the
following examples.
Example 2 -- Unsigned Output Quantity, Negative Slope
•
[Analog Out1 Sel] = “Output Current”
•
[Analog Out1 Lo] = 9 volts
•
[Analog Out1 Hi] = 1 volts
10V
[Analog Out1 Hi]
[Analog Out1 Lo]
0V
0% 200%
Output Current
Analog
Output Voltage
Output Current vs.
Analog Output Voltage
Marker Lines