Cannot read some tags inside Rockwell AOI

Ignition Early Access
24

Well, I usually use three UDTs for my AOIs. The AOI gets the base name (xyz, perhaps) for its functionality. The others:

  • xyz_fbk This is the collection of values that present the process variables, indicators, trigger integers, etc. Subscribed in Ignition with a fast pace, or mapped through my E/IP module from a PLC output buffer.

  • xyz_cmd This is the collection of setpoints and command bits and handshake short integers. Subscribed as needed (slow/leased is fine), but usually mapped to a PLC input buffer with E/IP. If so, can contain momentary buttons driven from my custom component.

  • xyz_cfg This is the collection of configuration items for the AOI, like process/alarm limits, tuning constants, operating modes, etc. Subscribed slow in a leased scan class, so the traffic is only present when the user has the corresponding configuration UI open.

Note that Ignition never writes into the xyz_fbk data, and the PLC never writes to xyz_cmd. This is crucial to avoid race conditions. And it fits well with E/IP I/O configurations.

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