Indirect Addressing Question

Hi, I have an indirect addressing question that I just can't understand.

L #DB_Conn
T #iDB
OPN DB [ #iDB]
L #DB_Start_Addr

SLD 3
LAR1
A DBX [ AR1 , P#0.0 ]
= #Advance_INT

A DBX [ AR1 , P#0.1 ]
= #Retract_INT

A DBX [ AR1 , P#0.6 ]
= #Advance_IND

A DBX [ AR1 , P#0.7 ]
= #Retract_IND

A DBX [ AR1 , P#1.0 ]
= #Valve.Error

A DBX [ AR1 , P#1.1 ]
= #Valve.Both_M

A DBX [ AR1 , P#1.2 ]
= #Valve.Both_NM

A DBX [ AR1 , P#1.3 ]
= #Valve.Adv

A DBX [ AR1 , P#1.4 ]
= #Valve.Ret

A #Valve.Advance_PB
= DBX [ AR1 , P#0.2 ]

A #Valve.Retract_PB
= DBX [ AR1 , P#0.3 ]

DB_Conn is the datablock address and DB_Start_Addr is the starting address.
I also pass a In/Out #Valve UDT datatype because there is inputs as well.

When I use the Valve datatype, the indirect addressing does not work, but when I link the results direct to outputs (Advance_INT, ...) it does get results.
I am using TIA Portal.

Any ideas or what am I doing wrong?

Access to elements of UDT parameters uses AR1 and also modifies the DB register:

See simple example code:

Thanks a lot, I haven't picked that up

So there is no easy way to use UDTs inside FB without changing the status of AR1?

Assign/read your UDT variables to named variables in the temp area then you can use AR1 to access your DB indirectly using the named temp variables.

Thanks, that is what I am currently doing.
Just thought there was an easier way

hein123 said:

Hi, I have an indirect addressing question that I just can't understand.

L #DB_Conn
T #iDB
OPN DB [ #iDB]
L #DB_Start_Addr

SLD 3
LAR1
A DBX [ AR1 , P#0.0 ]
= #Advance_INT

A DBX [ AR1 , P#0.1 ]
= #Retract_INT

A DBX [ AR1 , P#0.6 ]
= #Advance_IND

A DBX [ AR1 , P#0.7 ]
= #Retract_IND

A DBX [ AR1 , P#1.0 ]
= #Valve.Error

A DBX [ AR1 , P#1.1 ]
= #Valve.Both_M

A DBX [ AR1 , P#1.2 ]
= #Valve.Both_NM

A DBX [ AR1 , P#1.3 ]
= #Valve.Adv

A DBX [ AR1 , P#1.4 ]
= #Valve.Ret

A #Valve.Advance_PB
= DBX [ AR1 , P#0.2 ]

A #Valve.Retract_PB
= DBX [ AR1 , P#0.3 ]

Click to expand...

Not to detract from your thread, but what is this language ?

Siemens Step 7 (300/400 series) STL (statement list)