A Rapid SCADA input-channel formula can evaluate channel status with Stat(), but the available evidence does not define which status represents a missing input, null value, or disconnected device. Treat the supplied expressions as status-driven display logic, not proof of a dedicated null test.
Evaluate the channel status
The supplied Boolean pattern tests whether the status is greater than zero and returns a numeric display value:
Stat() > 0 ? 1 : 0This expression returns 1 when Stat() is greater than zero and 0 otherwise. Because the evidence does not map individual status values to communication states, first observe the status with the device connected and again with the input absent. Confirm that the comparison changes in the required condition before using it as a connection indicator.
Display Off and On text
To render the Boolean result as text, configure the input channel with Format = Enum text and Unit = Off-On. The formula supplies the numeric selector, while the format and unit settings supply the displayed labels.
| Formula result | Configured display |
|---|---|
0 |
Off |
1 |
On |
Retain a previous valid value
A separate expression was supplied for obtaining the last correct value:
Stat > 0 ? Cnl : Val()The evidence presents Stat without parentheses here, while the status-test formula uses Stat(). It also does not define Cnl or Val(). Verify the accepted syntax and identifier meanings in the target formula editor before deployment; do not silently substitute this expression for a null detector.
Verify the configuration
- Record the evaluated status and displayed result while the channel has a valid input.
- Remove or otherwise reproduce the reported no-input condition, then confirm whether
Stat()changes across the> 0boundary. - Confirm that numeric results
0and1display as Off and On after selecting Enum text and Off-On. - If retaining a value is required, test the supplied last-value expression separately and verify its syntax in the installed formula editor.
FAQ
How do I check channel status in a Rapid SCADA formula?
Use Stat() in the formula. The supplied test is Stat() > 0 ? 1 : 0, but verify the actual status during the no-input condition because the evidence does not define the status codes.
How do I display Off and On instead of 0 and 1?
Select Format = Enum text and set Unit = Off-On for the input channel.
Can Stat() confirm that a device is disconnected?
Not from the supplied evidence alone. Compare the observed status with valid input and without input, then confirm that the formula changes state under the exact condition you need to detect.
