Beckhoff CX1010 first scan

Googled a little, but didn't quite find the answer. I need to detect first scan of device so I found out in Beckhoff documentation about this data type: SYSTEMTASKINFOTYPE(http://infosys.beckhoff.com/english...m/html/tcplclibsys_systemtaskinfotype.htm&id=) which, among other variables, contains firstCycle variable (System library).

I don't know if I am missing something but I can't find a function which I could use to retrieve this variable, and I have searched among all functions and function blocks in System library.

Hopefully soon I will be able to help others the same way I am getting help on this very, very useful forum

http://www.powermation.com/pdf/contrex/cx-1010-tech-ref-manual.pdf

There is a first PLC scan bit.
Descriptions of the groups of operands and discussion of the associated Control Parameters follow:
Bit 0 is the top of the stack, S0 (first entry point).
Bit 1 is the bottom of the stack, S1, (lowest level).
Bit 2 is fixed at the value of 0.
Bit 3 is fixed at the value of 1.
Bit 4 is set to a 1 for the first PLC scan after power-up.

Also look at 'A Pulse Generator - One Shot' in the manual. This can be done on an internal bit to represent the first scan.

Hope this is helpful,
Garry
http://www.accautomation.ca

I believe the OP was asking about the Beckhoff CX1010 which is an embedded PC controller, not the similarly named Contrex product.

Yep, I meant Beckhoff embedded PC

Just use 'SystemTaskInfoArr[1].firstCycle' as the bit in your ladder logic or ST logic

I have always thought that the way to do the "FirstScan" in TwinCAT is as follows:

1. Declare a global BOOL variable with the default value of 'TRUE'.
2. Set it to 'FALSE' at the very end of the program task.

several options available in codesys (twincat)
there is an event under tasks you can use called start.
you can use ladderlogic way, however i have to remark that when running several tasks you have to find a way to detect if task is done.
This has advantages so you can see which task is done.

So IF firstscan do initialisation: firstscan:=false; END_IF

LadderLogic said:

I have always thought that the way to do the "FirstScan" in TwinCAT is as follows:

1. Declare a global BOOL variable with the default value of 'TRUE'.
2. Set it to 'FALSE' at the very end of the program task.

Click to expand...

Seems pretty logical

TwinCAT 3 first scan bit

I found using the green triangle and red square to stop and start the PLC code running DOES NOT work for "first scan". First scan only seems to work after re-starting the Twin CAT runtime. First scan seems to mean first "Runtime started" scan. This caught me out for a while. The below worked for me. I set a TP timer to run if "bTest" NOT true. I gave the timer like 50 seconds to run because that gave me enough time to log on and monitor the timer actually running after restarting TC3 runtime..

VAR
fbGetCurTaskIdx : GETCURTASKINDEX;
bTest : BOOL;
END_VAR
fbGetCurTaskIdx();
bTest := _TaskInfo[fbGetCurTaskIdx.index].FirstCycle;