
The Device Server Signal Interface
2. Conventions on Signals
The signal class allows the creation of signal objects with a naming convention as:
DOMAIN/FAMILY/MEMBER/SIGNAL
The signal name is an extension to the device name used in the ESRF control system. To create a signal object a name with four fields must be used. This corresponds to signal naming as it is used in the history database and in general data display applications.
- A signal represents a simple data value.
- All signals of a class must be of the same data type.
- The data type might be long values, float values or double values.
A special problem is the relation between read and set values and the command used to change a setpoint. This problem is not yet addressed in this release, but will be addressed in the near future. A fourth command seems to be necessary to send a list of set signals to a device. Also it seems to be necessary to extract from a read signal whether a setpoint is available and what is its name.
For the SRRF3 project we made only the following convention as a temporary solution:
- If the name of the readpoint signal is:
SR/RF-FOC/TRA3-1/Voltage
- the name of the setpoint signal must be:
SR/RF-FOC/TRA3-1/set-Voltage
- and the command to change the setpoint must be:
DevSetVoltage
With this convention always containing the signal name, the command for the setpoint can be determined.
The Device Server Signal Interface - 27 FEB 1998

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