Siemens STL explanation

thomassorensen · Feb 25, 2013

Hi Guys

I am trying to figure out, what exactly is happening in the below code.
I can see that they are looping through all the errorbits in DB50, but I am unable to figure out what they are doing with each bit.

Code:

      L     #NUMBER_OF_ERRORS   
M001: T     #ERROR_NUMBER     

      +     -1                          // 1 SUBSTRACT AS BIT START AT 0.0 AND NOT AT 0.1
      LAR1  

      OPN   DB [50]      		// OPEN error DB

      A     DBX [AR1,P#0.0]   

      OPN   DB [55]			// Open acknowledge DB

      TAR1  
      SLW   3                        
      LAR1                         
      =     DBX [AR1,P#0.0]             

      L     #ERROR_NUMBER
      LOOP  M001

STL??? · Feb 25, 2013

The code checks for active error bits in DB50 and then sets the corresponding acknowledge bit located in DB55.

L D[AR2P#0.0] · Feb 25, 2013

The bit number for DB50 is incremented, but for DB55 the byte number is incremented, e.g.

Code:

A DB50.DXB0.0
= DB55.DBX0.0
 
A DB50.DBX0.1
= DB55.DBX1.0
 
A DB50.DBX0.2
= DB55.DBX2.0
 
etc....

STL??? · Feb 25, 2013

L #NUMBER_OF_ERRORS
M001: T #ERROR_NUMBER
+ -1 // Align with 0.0

// Load into address register 1
LAR1 OPN DB [50] // OPEN error DB

// And DBX[ERROR_NUMBER,P#0.0]
A DBX [AR1,P#0.0]

OPN DB [55] // Open acknowledge DB

// Transfer Error_Number back to Accumulator
TAR1

// Shift left 3 places to enter Byte area
SLW 3

// Load back into Address Register 1
LAR1

// = DB55.DBX [Error_Number,P#0.0]
= DBX [AR1,P#0.0]

// Load Error_Number into Accumulator
L #ERROR_NUMBER

// decrement 1 and jump to Label M001 until zero achieved
LOOP M001

STL??? · Feb 25, 2013

L D[AR2 said:
The bit number for DB50 is incremented, but for DB55 the byte number is incremented, e.g.

Code:

A DB50.DXB0.0 = DB55.DBX0.0 A DB50.DBX0.1 = DB55.DBX1.0 A DB50.DBX0.2 = DB55.DBX2.0 etc....

Whoops missed that..

RRobbins · Feb 25, 2013

It's been a while since I used S5, LOOPS and JUMPS. I don't see where you are jumping out of the loop to prevent timeout errors. You always have to be careful about jumping UP in a program loop as to not get caught in an endless loop.

KalleOlsen · Feb 26, 2013

t

RRobbins said:
It's been a while since I used S5, LOOPS and JUMPS. I don't see where you are jumping out of the loop to prevent timeout errors. You always have to be careful about jumping UP in a program loop as to not get caught in an endless loop.

This is not S5 but S7.
The LOOP instruction decreases AKKU 1 with 1 and loops to the label M001 until AKKU 1 is zero. The ERROR_NUMBER is used as loop counter.

Kalle

Siemens STL explanation

thomassorensen

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L D[AR2P#0.0]

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RRobbins

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