FTalk Tag Bit Access

[DamianInRochester]

As an example, if i create a tag in the PLC called "tag1" as a DINT, and then reference several times that tag at the bit level in FTalk, does the PV sample the entire tag everytime I look at a bit, or does it recognize that it already has the entire DINT.

To put it differently, if I have indicators on a screen with connections referenced as follows


{::[L35E]Program:Test.tag1.0}
{::[L35E]Program:Test.tag1.1}
{::[L35E]Program:Test.tag1.2}
{::[L35E]Program:Test.tag1.3}
{::[L35E]Program:Test.tag1.4}
{::[L35E]Program:Test.tag1.5}

Is the PVP "wise enough" to recognize that is already has
{::[L35E]Program:Test.tag1} and doesn't need to call for it everytime I want to look at a bit in it?

 

[DamianInRochester]

Can anyone think of a clever way to test this?

 

[rdrast]

It will update it at whatever update rate is configured in your OPC server. And the OPC server will always read a full 32 bit word at a time.

 

[DamianInRochester]

It will update it at whatever update rate is configured in your OPC server. And the OPC server will always read a full 32 bit word at a time.

Thanks, but that's not really what I was asking.

I want to know if FTalk is bringing {::[L35E]Program:Test.tag1} in as a DINT, and doing the BIT stuff on the PV end (per update rate), or if it is accessing each instance of {::[L35E]Program:Test.tag1.X} as a bool tag. I realize that even bool tags will be treated 32bit, which is exactly why I don't want it getting it one bit at a time or making several calls every update for the same information.

I could put in an expression something like
{ModbusTCP.EPP.FaultBitMap1} & 8 <> 0
which I have done for bit access when communicationing with non-AB devices, but the bit level syntax minus the expression is a lot less work and probably less of a burden on the PV.