32 • SMP Gateway User Manual
Binary outputs
A physical data point represents a real-life value, implemented on an external device. You need
to identify all the device data points, either manually or using a device template.
A logical data point is a value managed by the SMP Gateway. These data points are built-in and
cannot be modified, but they can be disabled.
Analog inputs are measured values. The system keeps 2 values for each analog measurement
obtained: a raw value, which is usually the value retrieved from the device, and a calculated value
expressed in engineering units, obtained using the following standard formula:
Engineering value = Raw Value X Scaling Factor + Offset
Binary inputs represent the state of a data point. The state is either ON or OFF.
Analog and binary outputs are typically initiated by a slave component, which sends a control
request originating from a control center, to the master component involved.
When you create a data point, you specify the type of data and you indicate how the
SMP Gateway will retrieve it. General properties such as name, type and units, are independent of
the type of device or protocol used. Protocol-specific properties indicate how the SMP Gateway
will retrieve the data from the device. Each protocol uses its particular form of addressing, such as
index values or data offsets.
For example, to add a data point for a MODBUS device:
Click the appropriate branch under the protocol instance.
In the right pane, type the name of the data point and fill in all the appropriate settings.
For instance, to define an analog input you would provide the following settings:
The name of the data point, such as BUS_VA. SMP Config will automatically add the
device prefix to this name, thereby generating the full name of the data point.
The input source, such as Input Registers.
The input format, such as Unsigned Integer.
The input size, such as 16 or 32 bits.
The word offset in the MODBUS device memory.
The scaling information required to convert the raw value to engineering units.
The Units and Description strings used to provide meaningful data displays.
A complete description of all settings is provided in the document entitled Master Protocol
Common Concepts. Protocol-specific settings are described in individual documents, such as
Modicon Modbus Master Protocol. A complete description of system data points can be found in
the section entitled “System Data Points” on page 231 of this manual.
To acces
s the various protocol documents:
Click Start, on the Windows taskbar.
Point to Programs, then Cybectec, then SMP Tools, and then Documentation.
In the Documentation menu, click Protocols.
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