Multi-Tech Systems 7500 - Manual (Page 227)

ION 7500 / ION 7600 User’s Guide Setting Analog Zero and Full Scale Values
Digital and Analog I/O Technical Note Page 227
Detailed Operation
The following illustration shows the operation of a Analog Output module. The
Source input falls between the Zero Scale and Full Scale values. It is scaled and the
result is then sent to the specified hardware port. (The port is specified in the Port
setup register.) The Normalized output register provides information about the
state of the hardware: the output on the hardware port in this instance is at 83%.
If at any point the input rises above the value specified in the Full Scale setup
register, the output remains at the Full Scale value and the maximum possible
value is sent to the hardware port. Likewise, if the input falls below the value
specified in the Zero Scale register, the output remains at the Zero Scale value and
the lowest possible value is sent to the hardware port. If the input becomes
NOT
AVAILABLE , the Normalized output register is also NOT AVAILABLE and the lowest
possible value is sent to the hardware port.
Setting Analog Zero and Full Scale Values
You control or monitor external analog devices by delivering or receiving a
specific current or voltage that is proportional to a source. This is done by setting
the Full Scale and Zero Scale setup registers and defining the hardware port that
receives (Input) or delivers (Output) current. Use Designer software to configure
the setup registers in the Analog Input or Output modules.
When scaling values to current, the Full Scale value is always set to the highest
value you expect. The Zero Scale value depends on the actual current that drives
the input/output and the type of information that the current represents. The
following information steps through scaling an Analog Output module that
receives kW as a source and passes the kW value to an analog device whose range
is different than the range for the ION analog output.
N OTE
The general behavior of Full Scale and Zero Scale is such that: if the input rises above the Full Scale value,
the output remains at the Full Scale value and the maximum possible value is sent to the hardware port.
Likewise, if the input falls below the Zero Scale value, the output remains at the Zero Scale value and the
lowest possible value is sent to the hardware port.