I have a need to access individual Bits of a DINT tag on a ControlLogix PLC From Ignition. In the RSLogix environment you simply add .0 (or whatever bit you want) to the end of the tag. What is the correct syntax for this using the IgnitionOPCUA driver?

Currently there is no support in the ControlLogix driver for accessing bits of a DINT. The solution to this is use an Alias tag in the ControlLogix and will work with other data types beside DINT. See the attached image for details of how to add an Alias tag. [image]

[quote=“Kevin.Herron”][quote=“ISDProj”]Carl, Does the “Slash notation” work with ControlLogix PLC’s? I was under the impression that it was only for SLC & PLC style processors.[/quote] Slash notation only works on MicroLogix, PLC-5 and SLC-505. For ControlLogix you can currently use bit=X to read…

OK, So it looks like “read OR Write” is how we are going to handle this… :cry: [quote]It’s not possible to do a safe/atomic write to a bit without native support from the driver/device. [/quote]I assume that you are talking about the IA driver here, or is the “dot” notation an RSLinx only specialt…

Our core ControlLogix driver will support dot notation for both reading and writing. But we do have to make some modifications to have it tie into the OPC server and work with Ignition. We should have these changes done in the near future.

[quote=“thechtman”]Our core ControlLogix driver will support dot notation for both reading and writing. But we do have to make some modifications to have it tie into the OPC server and work with Ignition. We should have these changes done in the near future.[/quote] At the risk of sounding “pushy”…

This is starting to become urgent now… Do you have any timeframe for the read/write of the DINT bits yet (note this is specifically required for ControlLogix Processors) Don’t mean to “harp” on this issue, it’s just that I am a lowly PC programmer & have very little say in how our PLC’s are progr…

After some rather “lengthy” discussions with one of our resident PLC programmers I have managed to convince him to supply me with “BOOL” tags for the bits we need to control/read for this project. I’m relying on his expertise here as he states that this has consumed quite alot of extra PLC space (ap…

hmmm, I have seen some huge programs in the controllogix line, and none have used bit packing. I would bet that the programmer was a little more worried about the extra programming time as opposed to the “extra PLC space”. unless your plc program is ginormous I would be surprised if it is really an …

We use bit packing into DINTs for our first out and horn logic. One program has 3000 bits packed into DINTs. DINT packing is still used in the CLX line, especially if you are using remote comms via some legacy network protocol

yeah, I do use bit packing for first out logic, but I just havent seen much of it for comms anymore, should have been more specific. used to be we used it alot in the offshore environment due to limited communications options. thats not really an issue anymore.

Inductive Automation Forum

How do I access individual Bits of a DINT?

Ignition

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