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Power-up and password system bits in samba

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I am programming my first Unitronics product and I am having some issues...


I have a SM35-J-R20 PLC and the system bits 2, 250 and 251 seem to not be working... I have tried to connect them to toggle coils which in turn activate a MB. I use this MB to turn on a LED on-screen (my simplest attempt, I have tied many other methods) and nothing...


Does the Samba not work with these bits? Is there a common bug/user error that could cause this?


Thank you beforehand.  ;)

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SBs 250 and 251 are intended for the Standard Series Vision controllers, so they will not accomplish what you're looking to do.


On more recent controllers those system bits have had their function replaced by the "Legal Entry" Link on almost all on-screen elements you'll use.

Previously, the standard series controllers did not have that "Legal Entry" link, so SB 250 and 251 were required.


SB 2 will only be high for a single pulse on power-up.  SB 2 is perfect for running one-time configuration/initialization whenever the controller is turned on. 




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You can find System Bits descriptions in Help->Operands->System Operands.

SB 2 is active only for the first system scan after powering PLC on.


SB 250 and SB 251 are active for Standard Vision without touch screen, not for Samba, as explained in Help.


You can use SI 45.

What exactly do you wish to do?


You can use disply elements, such as Binary Text, Binary Image, Button, etc., link them to MB and realize your logic.


It will be useful to watch webinars to be familiar with PLC.

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Thank you for your answers.

I figured out the password field issue, I managed to implement the functionality I was looking for.

The SB2 still has me a little baffled... I attempted to switch a coil on at boot for testing purposes, as well as the logic shown in the hmi tips and tricks webinar for splash screen. None of them worked, it's like SB2 is dead. Clues?

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