Regardless of the generation of SCADAPack and the programming software being used, there are two main situations where a coil or digital output may appear to be energized in logic but that the physical digital output and LED do not energize.
In all SCADAPacks, the physical I/O needs to be associated to an appropriate point in logic.
- In RemoteConnect for a SCADAPack X70, the IO Configuration needs to have an Object associated with an IO Channel
- In this image, the Object Association shows that PIO_SP474_DO1 is mapped to Channel DO1. Note that Channel DO2 does not have any Object associated with it. So even if there was still an Object PIO_SP474_DO2 in the object database, it would not control the physical digital output in this circumstance.
- Similarly, SCADAPack Workbench (for SP32 and SP3xx) uses the I/O Wiring to associate a variable name with a physical IO point
- And finally, TelePACE Studio (for SP32 and SP3xx) uses the Register Assignment feature in order to map the physical IO to Modbus registers. A TelePACE Studio project without a suitable register assignment will not be able to monitor and control the physical IO.
In all SCADAPacks, the final step in a logic cycle is to update the physical outputs
- In all varieties of SCADAPack, the logic generally follows this routine:
- Read the current state of digital and analog inputs
- Perform a scan of the logic
- Update the digital and analog outputs
- In a situation where a coil appears two or more times within the logic, the controller will update the physical digital output according to the last scanned instance. For a TelePACE Studio example:, Network 1 shows that Coil 1 is energized but Network 2 shows that Coil 1 is de-energized. By observing Network 1, a technician might think that the digital output should be ON
- But because of the coil state in Network 2, the physical digital output will remain OFF
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