JiM_cz

Difference between RUN and MONITOR modes

3 posts in this topic

Hello guys.

I have just a basic question. What is actually  the difference between Run and Monitor mode of the PLC? I know that when I want to change the mode I get a message informing me that the mode will be changed and I should make sure it's safe. But what an "unsafe" situation might happen? I've changed the mode many times when I needed to do online changes or to force a bit and never had any problems with the running machinery.

In the manual I've found many times a note that " When the operating mode is changed between PROGRAM or MONITOR mode and RUN mode" some memory areas will be cleared but again, I've never experienced any strange behavior of the machinery.

Last thing. If I leave the PLC in Monitor mode permanently (instead of returning back to Run mode) is there any downside?

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Monitor mode allows online program changes - run does not. I start all mine in monitor mode anyway.

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Monitor mode allows for some memory areas to be monitored from outside commands.  Monitor mode allows you to force bits on and off and to set values in memory addresses using CX-Programmer (see my first note).  I will also set the PLCs to power up in monitor as a rule of thumb.  

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