Configuring a UIS Command
Note: Topics in the table of contents that end with an asterisk (*) indicate that they relate only to the Modbus protocol.
A Universal Interface Service (UIS) command is a user-defined remote device property that enables the getting and sending of data to and from a field device. You can poll data groups manually from the remote device editor for set up and testing purposes. But UIS commands enable automated and scheduled getting and sending of large amounts of data at regular intervals. The automated exchange of data means that alarming and historization are efficient and dependable.
All interaction between a CygNet host and a field device is done through the use of data groups and associated UIS commands. UIS commands can be defined at the remote device or linked facility level. Being able to define a UIS command at the linked facility level enables the application of the settings of one UIS command to multiple facilities, a useful and necessary feature of a templated environment. The combination of the command name and facility ID used to define a UIS command must be unique.
Using either the DDS or CygNet Studio, you can request data from or send data to a field device by using a designated button. However, using a button is a manual process and is not always practical, particularly if you want to retrieve data on a scheduled interval. Alternatively, UIS commands can be scheduled using the Master Scheduling Service (MSS) if the command’s Can Schedule option is enabled. The MSS setup is used to automate the sending and receiving of data group information. Finally, UIS commands can be executed using script.
When you send a command to a field device, the field device responds with at least an acknowledgment (handshake). Commands to get data require field devices to respond to the UIS with the requested data. Data group tags associated with the command components are then updated with the new data. Commands to send data require field devices to respond to the UIS with an acknowledgment. Data group tags associated with the changed command component parameters are updated based on the acknowledgment.
If you want a field device to return data in addition to the send acknowledgment, add a command component to get data. Use any component that contains the correct parameters. For example, the value in an analog output command can be retrieved using the analog output data group or a basic poll. If you don’t want an acknowledgment to update a tag, don’t map UDCs to the send data group. Instead, map them to the get data group.
For information about using CygNet Studio and UIS commands, and monitoring the status of a UIS command with a Status Point, see UIS Command Button Tool.
For information about scheduling automated commands, see UIS Command Task.
More:
UIS Commands and Device Template Files
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