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Hi Shamus, If your FB works fine with only one motor, then all you need is separate DB for every additional motor. There is also other, a little bit more sofisticated way to achieve your goal. You can create STAT variables of type FB100 in other FB block. In code you simply call this variable like normal FB but without instance DB. It saves DB address space. Copy this code to STL source and compile it to see how it works. FUNCTION_BLOCK FB 100 TITLE = VERSION : 0.1 VAR_INPUT in1 : BOOL; in2 : BOOL; END_VAR VAR_OUTPUT out1 : BOOL; out2 : BOOL; END_VAR BEGIN NETWORK TITLE = END_FUNCTION_BLOCK FUNCTION_BLOCK FB 1 TITLE = VERSION : 0.1 VAR motor1 : FB 100; motor2 : FB 100; motor3 : FB 100; END_VAR BEGIN NETWORK TITLE = CALL #motor1 ( in1 := I 0.0, in2 := I 0.1, out1 := Q 0.0, out2 := Q 0.1); CALL #motor2 ( in1 := I 0.2, in2 := I 0.3, out1 := Q 0.2, out2 := Q 0.3); END_FUNCTION_BLOCK

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If you're talking about Step7 then the answer is: yes. Open the project. In the navigation pane unfold the project tree so you can see the Blocks folder. Right click it and choose Object properties.... Go to Address priority tab and select "For all accesses. After changes do not forget to compile whole project.

Next time try to compress memory first. See Step7 online help.

What do you mean by an expansion rack ? Is it a S7-400 ER or UR rack ? If so you need to use a pair of IM460/IM461 modules. I've never heard of kind a "DP slave" module for S7-400 (something similar to ET200M). It's also posible to use a CR/UR rack with a S7 CPU configured as a DP slave. However this option might be "over engineered" in your case... If you have to use Profibus DP then maybe ET200 or other remote IO system is the way to go for you ?

Check S7 LAD/STL/FBD editor Options->Customise...->View->View for Block Types->Logic Blocks: if it's not set permanently to STL. To change viewing mode: menu View and choose between LAD/STL/FBD.

Which flavour of Siemens do you use ?

Well, people usually don't remember/know that the code below works well only when real_number is in range <0.0 .. 32767.0>. (OK, with RND it works well in fact for numbers in range <-0.5 .. 32767.5) but it does not change much) L real_number RND T int_number

Generally speaking - no, you can't.

It can be either MPI or Profibus. But you need at least a MPI adapter to connect to your PLC.

Well, yes and no. If you have proper communication hardware and software like ProtoolPro or WinCC flexible, then yes. If you do not have them - then no.

Which version did you try to install ?

You could also try a soft PLC like TwinCAT from Beckhoff. It has built-in simple HMI, so you can simulate real IO with it. And you can evaluate it for free as long as you wish (30 days after each installation).

Solution with OB35 has +/- 200us jitter. I'd say it's a lot. But in the end everything depends what is to be achieved. Dear iic_hyd, you should elaborate a little bit more on your requirements.

TwinCAT does not support DDE - or I've never heard it does. To access its variables out of other OLE soft use OPC. There's a trial version of their OPC server.