Dave, Just out of interest I replaced the toggle node in the lower flow with the one Alan attached below and the button display now switches back and forth consistently with one press, even though the lower flow is switching between 1 and zero rather than "true" and "false". I've no idea why yet as I've not looked at the json on your toggle or Alan's toggle. Whereas before it would take two button presses in one direction. This may or may not help as it's not Modbus messages. I just linked the upper and the lower flow together and switched out the toggle in the lower flow.
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Of course, looking at your toggle json, that may not be what you were trying to achieve. i.e if was already red then leave it red, don't switch it to green and vice versa.
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73 de G8PFR
Mike
gibsonmb