Hi all,

We are using Siemens D435 - 2DP/PN for our project. We have one s71200 PLC (1215 DC/DC/Rly) which is communicating to our custom software in a PC through OPC.

The overall communication structure will resemble like below,

PC     ------------------------>      PLC  ---------------------------->  Simotion D435

In simotion drive we have six motion tasks each for one axis. We have altogether 6 axis in our project.

Each program in these task are started by a background task program and after that it will continue to run till drive power off. We have placed a goto statement before end sothat the program will not end until power off/errored.

When the custom software in PC wants an axis to move to a target position, it will change the corresponding variables (start(bool) targetPos(Dint) ,velocity, acceleration(Dint)) which is shared between PC and PLC(OPC variables). The PLC inturns copy corresponding value to drive input address . If the start variable is true , then the corresponding action will get executed .

The problem which we are facing with this approach is that , most of the times axis will move when we change the start variable to true . But sometimes it misses it and doesnt move to target position. We tested the PC PLC OPC interface and we are much confident that the variable on the PLC side is changing . Now the real thing which we are suspecting is the communication delay between PLC and drive side.

By the time drive execute the motion command , the target position is not updated and it will execute the command with old target position value. Is there any way to ensure that all the input output variables are updated before the corresponding command execution. Which means that the target position, velocity and acceleration must be updated before the motion command execution

Can anyone advise us in this matter. Thanks in advance.

Hi,

Yes its a I-Device communication

Hi,

Will it guarantee that all the Input output variables will get updated before task execution.

Also if i have a while loop inside motionTask which runs for say 5 minutes , how will it affect my execution system.? Will it block other task status/ communication tasks?

In my motion task program for jog operation , we are checking it in a while loop(whether the jog variable is true or false)

Hi,

If i call a motionTask from IPOSynchronous task will it work?

No idea.  This is why I don't use Motion Tasks since they are low priority.

jerryvdk

By the time drive execute the motion command , the target position is not updated and it will execute the command with old target position value. Is there any way to ensure that all the input output variables are updated before the corresponding command execution. Which means that the target position, velocity and acceleration must be updated before the motion command execution

Can anyone advise us in this matter. Thanks in advance.

 One solution can be checkback - ie. you write e.g.new target position to Simotion, which in turn copies the value to another var, which you read. While both vars (written and read) are equal, you are sure that the data is already updated in Simotion.

jerryvdk

If i call a motionTask from IPOSynchronous task will it work?