Modbus Address - Read and Write

[Coleman_Dudley]

Good Afternoon Everyone,

Thanks for helping me in the past with the Modbus Addressing.

My addresses as of now are read only. For example, [MB3170-Flow_Meter]1.HR338 and relates to changing units in the flowmeter (Holding Register in which is able to be read and written). I would like to change this address to a read/write through Ignition. I have read Tag Security Properties | Ignition User Manual for help which is straight forward, but I want the user to only be able to select certain values. The values would range from 0-19 which can be seen below. Do you have any pointers on how I would set this up?

IM01E21A02-05EN (2) - Modbus.pdf (2.3 MB)

Thanks again,

C

[Felipe_CRM]

You could use a drop down so only the valid values are even available to choose. As a bonus, you could set up the drop down menu with the actual units to make it more clear to the user.

If you're trying to restrict changes through the Designer as well, a value change script could check if the new value is valid and change it back to the old value otherwise. This would obviously only help against accidental changes as if a user with malicious intent/reckless curiosity has access to the Designer there's very little they can't do.

[pturmel]

Enable scaling, but set it to 1:1, then set min and max and enforce the limits.