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PWM use

Created by: Highlag at: 5/17/2010 11:50 PM (13 Replies)

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5/17/2010 11:50 PM	Rate (0)
Highlag Posts: 3 Rating: (0)	Well first off, I'm beginner, done just a tiny bit of work with 300 series. I would like to use Hardware PWM, as I have the module installed. Nothing fancy, just constant clock source say 200Hz, 50%. I have enabled PWMs in hardware configuration, and set up: Pulse generator used as: PWM Output source: signal board output Time base: milliseconds Pulse width format: Hundredths Cycle time: 5ms Initial pulse width: 50 But I'm lost with configuration. I've done some search on how to do this, but found nothing of use. I know I must set Cycle time and pulse width, but nothing specific is written how to do that. PWMs are as far as I can tell on Q4.0 and Q4.2 What to select on PWM / Enable / Status pins OB1 block? Can anyone give an example? Regards!
Highlag Posts: 3 Rating: (0)
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5/18/2010 3:51 PM	Rate (0)
billwest Posts: 510 Rating: (120)	I have attached 3 pages from the 1200 Easy Book to get you started. Q4.0 is the address if you have a signal board installed. Q0.0 and Q0.2 are the outputs on the 1200 I/O. Use the CTRL_PWM block to start and stop the pulse output. Good Luck, billwest Attachment PWM Pages from s71200_easy_book_en-US_en-US.pdf (1218 Downloads)
billwest Posts: 510 Rating: (120)
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5/18/2010 5:02 PM	Rate (0)
Highlag Posts: 3 Rating: (0)	I'm sorry to say that I've read manual specially PWM section number of times. With no avail. Is there any literature to look / buy where I can get more detailed info? I want to know details for example where exactly I can input pulse width and how. Where can I select which pwm output certain PWM_modul uses?
Highlag Posts: 3 Rating: (0)
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5/18/2010 9:57 PM	Rate (0)
Highlag Posts: 3 Rating: (0)	To answer myself. First in hardware configuration: Find module: Pulse_1. ( and Pulse_2 if necesarry) Parameter assignment must be set to PWM Output source to Signal board output. One must also set parameters for time base - which determines PWM frequency -> , Timebase (milli/micro seconds), cycle time (, pulse width format (100 / 1000 / 10000 / S7 format) and initial pulse width. For example if pulse width format is 100 then pulse width 50 will give signal with duty cycle 50%. Frequency is if you set Timebase to miliseconds and set cycle time to 5, your frequency will be 1/0,005s=200Hz Check and note Hardware output. Then in program block (OB1 or whatever), insert CTRL_PWM block. EN pin connect to left wire, PWM pin connect to desired Hardware Pulse pin (Pulse_1[PTO/PWM] for example) ENABLE connect to contact which will start PWM to output ENO pin wire co Coil, which you recorded previously in hardware configuration under hardware output. Not sure if all written is correct procedure, but both of my PWMs work this way. Now if I could only regulate Pulse width somehow...
Highlag Posts: 3 Rating: (0)
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5/20/2010 5:44 PM	Rate (0)
billwest Posts: 510 Rating: (120)	The PWM configuration includes the output address. It is located above the Hardware Identifier in the device configuration. This address is used to change the initial pulse width.You use the Enableof the CTRL_PWM to turn the output, Q4.0, on and off. You use the output address to change the pulse width. I have attached 3 slides from a training presentation that includedPWM. Hopefully this will resolve your questions. Good Luck billwest Attachment Pulse Width Modulation (PWM).pdf (1129 Downloads)
billwest Posts: 510 Rating: (120)
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11/26/2013 2:19 AM	Rate (0)
cosmosk Posts: 10 Rating: (0)	Hi, I'm just starting with the S7-1200. I have a Relay CPU and an SM 1223 signal board. The former prevents me from using PWM/PTO or motion control of an axis as far as I can tell. From what I'm reading, I'm led to believe I can run it off the dignal board, but I cannot set the Output Source to anything. It is grayed out as "Intergrated CPU output". Where I'm seeing this is after double clicking on the PLC in the device view. Double clicking on the signal board only shows DIs and DOs and no Pulse Generators to configure. Any ideas? Thanks
cosmosk Posts: 10 Rating: (0)
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11/26/2013 2:46 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/23/2025 Posts: 15553 Rating: (2467)	cosmosk Hi, I'm just starting with the S7-1200. I have a Relay CPU and an SM 1223 signal board. The former prevents me from using PWM/PTO or motion control of an axis as far as I can tell. From what I'm reading, I'm led to believe I can run it off the dignal board, but I cannot set the Output Source to anything. It is grayed out as "Intergrated CPU output". Where I'm seeing this is after double clicking on the PLC in the device view. Double clicking on the signal board only shows DIs and DOs and no Pulse Generators to configure. Any ideas? Thanks Relay outputs cannot operate fast enough and clean enough to drive pwm/pto so you cannot use them with that cpu. If you have a dc output signal board, you may be in luck. If you want pwm/pto, get a dc output plc rather than rly output. If you need relay output, add a relay output module to the plc rack.
	science guy
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11/26/2013 6:45 PM	Rate (0)
cosmosk Posts: 10 Rating: (0)	I'm led to believe I should be able to run it offf the signal card, but I'm not finding any evidence of that in reality. There's talk of being able to configure the output but it seems to be automatic on my end. Maybe the relay CPU prevents the signal card from being used to that end. I will look into getting another CPU Thanks
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11/26/2013 7:32 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 1/23/2025 Posts: 15553 Rating: (2467)	cosmosk I'm led to believe I should be able to run it offf the signal card, but I'm not finding any evidence of that in reality. There's talk of being able to configure the output but it seems to be automatic on my end. Maybe the relay CPU prevents the signal card from being used to that end. I will look into getting another CPU Thanks I tested your findings and found the exact same thing, Portal V12 will not allow you to configure a s7-1200 signal board as a high speed control output. Since this is a feature mentioned in the s7-1200 documentation, I would submit it as a Support Request. Let us know what they respond with, either work-around or future firmware/software fix.
	science guy
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11/26/2013 7:54 PM	Rate (0)
cosmosk Posts: 10 Rating: (0)	Thanks for your help! I sent in a support request. I'll report back with what they tell me.
cosmosk Posts: 10 Rating: (0)
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