Issue:

What is the effect of selecting the M340 PLC configuration parameter 'Initialize %MWi reset on cold start' ?

Product Line:

Modicon M340 PLC

Resolution:

Cold Start =  going from Unconfigured to Configured.

If you Transfer a project to an M340 that has a configuration with State Ram, Scenario 2 will leave existing state ram data unchanged.
If you power up an M340 with no SD card and then insert the SD card, Scenario 2 leave all data at 0.

1. When checked, those %MW 's with initial values will be loaded. Any %MW not having an initial value will be cleared (initialized) to 0.
2. If unchecked the all %MW's are cleared to 0 regardless of the presence of initial values.
3. Unlocated variable values are maintained regardless of whether this box is checked or unchecked.

If you need to maintain 'current values' when transferring a project to an M340 that already has a program, the box must remain unchecked. In this scenario, if the program is lost at the PLC (CPU or SD card failure) when transferring to the new PLC, no located data will be loaded. If the State Ram values in the M340 have importance, it is recommended to 'Save Data from PLC to file' so that state ram it is available in the event of a full transfer to an unconfigured M340.