what is Watch dog,self -checking

tnkanth

Member
Join Date
May 2006
Location
Banglore
Posts
2
Hi all​



i am not having clear idea on the following terms related to PLC.​

any one of you please clarify me in this.​

What is self documenting type (in PLC/DCS).

the setpoints........ can be changed only via programming tool(notebook)."
what is note book?​

The system shall require a minimum or maintenance and shall have comprehensive watchdog,​

wat is watch dog?​
self-checking and self-diagnostic fault detection capabilities, to monitor the system hardware​

and software​


What is difference between self checking and self diagnostic fault detection.​
 
I have no idea what self documenting is - sounds like a great idea, though.

I assume they are using notebook as an older term for laptop PC.

A watchdog is a bit or register that is cycled on or off periodically. If the communications master doesn't see it change in a set time it knows that the communications link has failed. In other cases a watchdog is a bit that times out inside a single CPU to indicate that the scan is taking too long or has halted.

Self diagnostic to me implies that error codes are displayed or set when the self checking finds a problem.

This looks like somebody's shelf spec copied from a vendor's information. Find out what brand and model the customer is looking for and you can forget the BS.
 

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