Here a fun one for todays consideration

[theColonel26]

I found this code today in a running machine. This routine executes but the bit to call it is only written to inside this same routine... so how does this thing get executed?

What am I missing here?


See screen shots

 

[Mispeld]

Is File #4 also being executed by the system (i.e., check MCP tab of Processor Status), or another JSR?

 

[Aardwizz]

Best guess:

The HMI sets the bit. The routine executes and perhaps holds the bit true while it does what it does, which keeps the JSR live. When it's done, the OTE is de-energized, and the routine isn't called anymore.

 

[plvlce]

It probably says something about me that the first thing I notice is 'CALIBATE'

 

[theColonel26]

It probably says something about me that the first thing I notice is 'CALIBATE'

Yeah there is a whole of that in this guys programs. I noticed it right a way too.

 

[Operaghost]

Another possibility is that perhaps there is more than one JSR calling the routine. You can search for U:4 to see if there are any more.

As Mispeld mentions, you can configure the PLC-5 to have more than one Main Control Program (MCP). LAD2 is an MCP by default, but I think you can manually configure up to 16 MCPs in the Processor Status. If I recall, the tab is called MCP. But I don't have it open to be certain.

OG

 

[theColonel26]

We have a winner

FYI it is a ML 1100

Found a Second JSR using the Find Feature (thanks Operaghost for the hint )

 

[sharkyh2o]

Also check for indirect addressing. Search "[" to see if any exist.