Read only points

[craig]

Hi,
Some points, like process variables, are read only. Their value can't be set even if you are super-user.
I see there is the "settable override" in the graphical view and I can assign a user's permission on a point from SET to READ.

With more than a couple of users and potentially hundreds of points assigning the READ/SET property for each user becomes a lot of work!

Could this property be assigned to the point in the data source edit screen and be effective for all users?

If you think this is a good idea I'll get to work on implementing it
Craig

[mlohbihler]

Hi Craig,

It depends upon the data source, but some points can be explicitly indicated as not settable, while other points are naturally so. For example, you may notice that HTTP Retriever points are not settable. Virtual points can be explicitly set.

In which data source are finding that you cannot make point non-settable?

[craig]

Modbus IP.

[mlohbihler]

Whether a modbus point is settable or not is internally determined as so:

range == RegisterRange.COIL_STATUS ||
range == RegisterRange.HOLDING_REGISTER

I.e. coils and holding registers are settable, and inputs are not. I know there are few implementations of modbus that actually adhere to the spec's intentions, but according to the spec this should be sufficient.

I suspect you'll want an override checkbox or something?

[craig]

Hi Matt,
I did come across that snippet that assigns the settable property. Now I see that I should be using input registers instead of holding registers for the points which are read only. I was thinking of input register as "input to the PLC" which would make them writable and holding registers as "output from the PLC".

A checkbox/radio might still desirable in the datasource edit screen for setting the default permissions on a point but using "input register" instead of "holding register" as the register range will sort me out.

Thanks for your assistance,
Craig