What is the best way to implement a start button in Perspective? This button will control an OPC tag connected to an AB controller. In Vision, I'd have used a momentary button with an ONS instruction in the PLC. The bit could get stuck, but it wouldn't be a major issue like it could be for a hold-to-jog function, and the bit would only be written from Ignition, never the PLC, avoiding a potential race condition.
I can think of a couple possible solutions:
- Use the Perspective One-shot button. Reset the bit in the PLC.
- Writing from multiple sources seems to go against the conventional wisdom (at least here on the forums)
- Does this open up the possibility for a race condition?
- Writing from multiple sources seems to go against the conventional wisdom (at least here on the forums)
- Use the Perspective One-shot button. Set a handshake bit in the PLC. Monitor the handshake bit and use an Ignition script to reset the One-shot bit.
- Only writes from one source.
- Feels more complicated than it should be.
- Most confident that the PLC received the command.
- Use any component to fire a script (Button is probably the logical choice for this). Set the tag or OPC value in the script, wait some fixed time then reset the tag or OPC value.
- Only writes from one source.
- Most similar to the Vision solution I'm familiar with.
- Still seems more complicated than I'd expect.
I don't mind embracing complexity if it leads to a better outcome, but I wonder if there's an obvious way I'm not seeing. Thanks in advance for any thoughts or feedback.