koenb

Hi ,

If I need to track running time , I always count time . Then i have a real value in hhhhh.mm as it should be on a real timecounter
Easy to handle , display and modify ( synchronice with hardware )

koenb

 Dear Koenb,

I am a beginner in the PLC programming. I am trying to implement your logic to track the running time. But, I don't know exactly, how to save the signal state of the previous scan cycle(for "Clock_1Hz") in the edge memory bit. please help me to find this details.

Thank you.

with best regards,

Gajan.

------------------------------------------------------------------------------------------
Split from Running Time Calculation of Motor in plc from display on HMI.

William_B

 

Gajan.K

 

koenb

Hi ,

If I need to track running time , I always count time . Then i have a real value in hhhhh.mm as it should be on a real timecounter
Easy to handle , display and modify ( synchronice with hardware )

koenb

 Dear Koenb,

I am a beginner in the PLC programming. I am trying to implement your logic to track the running time. But, I don't know exactly, how to save the signal state of the previous scan(for "Clock_1Hz") in the edge memory bit. please help me to find this details.

Thank you.

with best regards,

Gajan.

 

From the example the "b525" is helping to remember that when a negative edge of "Clock_1Hz" is triggered.

For background information (you choose to use it / not use it) - look at RTM instruction.

 Hi William,

Thank you for your help. RTM runtime meter is easy to use. I also needed to implement a timer for long running time(ie: 45 days).

But, I am still not clear in that tag "b525". What should I assign to that memory?. I referred the siemens help of the instruction "--|N|--: Scan operand for negative signal edge". Mentioned that, operand 2 is the signal state of the previous scan. So, how to save the signal state? Please explain me to clarify the doubt.

Thank you.

William_B

 

Gajan.K

Hi William,

Thank you for your help. RTM runtime meter is easy to use. I also needed to implement a timer for long running time(ie: 45 days).

But, I am still not clear in that tag "b525". What should I assign to that memory?. I referred the siemens help of the instruction "--|N|--: Scan operand for negative signal edge". Mentioned that, operand 2 is the signal state of the previous scan. So, how to save the signal state? Please explain me to clarify the doubt.

Thank you.

You just have to make sure the storage bit (in this case: "b525") is a bit variable that is not used anywhere else in your program. It can come from M-memory, DB bit or STAT in an FB. Any bit will do.

The edge trigger instruction takes care of the rest. The "output" of the instruction is the required edge trigger. The inside may look something like the following instructions...

#result := not (#input ) and #memory;
#memory := #input;

In LAD it would be..

  #input              #result
---| N |----------------(  )
  #memory

So to re-cap... make sure the bit you use  is used only once and nowhere else.

Does this help?
w

 

 

 Hi William,

I designed the same instructions which are mentioned in this blog. The storage bit(b525) is used only once in that program.I also enabled the clock memory. But, the time of that counter doesn't increase. I attached the online status with this blog. Please help me to rectify the problem.

Thank you.

with best regards,

Gajan.

William_B

Does the %M0.5 even change?

Several issues can be the problem...
* The clock memory is not set in the hardware configuration.
* The hardware configuration was not compiled and downloaded.
* The clock memory overlaps with other memory bits / bytes / words.

I suggest move the clock memory to some bits you know was not used.. example MB1000. Change the program to adapt to the change. Compile the complete program and ensure the hardware is also downloaded.

There are some other minor issues I see - - but focus first on getting a pulse (heartbeat) from the PLC (patient).

w

 Hi William,

Thank you for your immediate replies to rectify my problem. Now, the time counter is working fine. I didn't compile and download the hardware configuration after enabling the clock memory. I just downloaded the software only. That was my fault.

Thank you again for the help.

With best regards,

Gajan.K