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Difficulty in modulating a PWM positioner valve using the S71200

Created by: SrRufino at: 1/19/2017 12:39 PM (3 Replies)

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1/19/2017 12:39 PM	Rate (0)
SrRufino Posts: 1 Rating: (0)	Bom dia Sr Denílson. Estou tendo dificuldade para modular uma válvula com posicionador PWM usando o S71200 com Signal Board com saída PWM (DQ4 signal board (200 kHz)). O dispositivo é para trabalhar com 200Hz, logo eu configurei o hardware da Siemens do seguinte modo: * signal type : PWM * out source : signal board * time base : microseconds * pulse format : hundredths * cycle time 5000 microseconds * initial pulse duration : 0 usando o programa padrão do exemplo da aplicação estou com o seguinte problema * eu habilito a saída PWM como já descrito. * ajusto a largura do pulso para 100% - a válvula abre dando saída da água do meu processo. * mudo a largura para qualquer valor entre (100 a 80)% e nada muda na minha vazão que continua totalmente aberta. * mudo a largura para 79% ou menos e a válvula tranca. Ainda não tenho nenhuma razão para acreditar que o problema e na válvula ou na aplicação. Tem alguma ideia para eu testar, antes de desistir desse modulo da Siemens? Obrigado Alexandre Rufino - AETTeam Denilson Pegaia Hi, do you use the output from CPU or from signal board? Did you have already tired tochange the time basis from miliseconds to microseconds? --------------------------------------------------------------------------- Translation by moderator: Good morning, Mr. Denilson. I am having difficulty in modulating a PWM positioner valve using the S71200 with Signal Board with PQM signal (200 kHz). The device is to work with 200Hz, so I configured Siemens hardware as follows: * Signal type: PWM * Out source: signal board * Time base: microseconds * Pulse format: hundredths * Cycle time 5000 microseconds * Initial pulse duration: 0 Using the standard application example program I have the following problem * I enable PWM output as already described. * I adjust the pulse width to 100% - the valve opens giving water out of my process. * I change the width to any value between (100 to 80)% and nothing changes in my flow that remains fully open. * Changes the width to 79% or less and the valve locks. I still have no reason to believe that the problem is in the valve or the application. Do you have any ideas for me to test before I give up this Siemens module? Thank you Alexandre Rufino - AETTeam ------------------------------------------------------------------------------------------ Split from TIP for S7-1200 und PWM.
SrRufino Posts: 1 Rating: (0)	Last edited by: Min_Moderator at: 1/19/2017 3:22:50 PM Add translation Last edited by: Min_Moderator at: 1/19/2017 3:23:30 PM New subject after splitting
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1/19/2017 3:43 PM	Rate (0)
William_B Posts: 5225 Rating: (1199)	SrRufino --------------------------------------------------------------------------- Translation by moderator: Good morning, Mr. Denilson. I am having difficulty in modulating a PWM positioner valve using the S71200 with Signal Board with PQM signal (200 kHz). The device is to work with 200Hz, so I configured Siemens hardware as follows: * Signal type: PWM * Out source: signal board * Time base: microseconds * Pulse format: hundredths * Cycle time 5000 microseconds * Initial pulse duration: 0 Using the standard application example program I have the following problem * I enable PWM output as already described. * I adjust the pulse width to 100% - the valve opens giving water out of my process. * I change the width to any value between (100 to 80)% and nothing changes in my flow that remains fully open. * Changes the width to 79% or less and the valve locks. I still have no reason to believe that the problem is in the valve or the application. Do you have any ideas for me to test before I give up this Siemens module? Thank you Alexandre Rufino - AETTeam ------------------------------------------------------------------------------------------ Split from TIP for S7-1200 und PWM. Hi Alexandre, I see no fault in the description you have given. Do make sure that compile / hardware (rebuild all). Then make sure you load hardware configuration to the PLC. Many times this little detail caused issues for others. Have you tested the PWM output on anything other than the valve? Maybe use a 1k.ohm 1W resistor. Measure the voltages over the resistor. The meter should give you averaged voltage reading.. you will see the voltage changing as the PWM width changes. The best would be to use a scope. When connected to the valve, you can repeat the measurement and see what you get. I have a feeling that you have a high impedance (ohm) on the valve side that causes problems for the SB. Double check: What SB do you have? 5V type or 24V type? 200Hz seems low - what is suitable for the valve? 800Hz / 1kHz / something else? (^{Opinion based on experience with other equipment - Best to read reply by huggy_d1!}) What voltage levels does the valve actuator expect? What is the entry impedance of the valve actuator circuit? Good luck.
William_B Posts: 5225 Rating: (1199)	Last edited by: William_B at: 1/20/2017 9:15:46 AM Add note in italic script after reading huggy_d1's contribution.
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1/19/2017 6:03 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 2/14/2025 Posts: 15653 Rating: (2477)	If 200 Hz is 100% flow, what Hz is 0% flow? You need to adjust your output over the valve's range, not 0% PWM to 100% PWM. 200 Hz seems on the higher end of PWM proportional valves, and not at all uncommon. You might want to look at the output on a scope as previously suggested. Use the CTRL_PWM block to turn the PWM output on.
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7/16/2021 4:46 PM	Rate (0)
Bruno_Bertotti_91 Advanced Member Joined: 9/1/2017 Last visit: 8/1/2022 Posts: 1 Rating: (0)	SrRufino Bom dia Sr Denílson. Estou tendo dificuldade para modular uma válvula com posicionador PWM usando o S71200 com Signal Board com saída PWM (DQ4 signal board (200 kHz)). O dispositivo é para trabalhar com 200Hz, logo eu configurei o hardware da Siemens do seguinte modo: * signal type : PWM * out source : signal board * time base : microseconds * pulse format : hundredths * cycle time 5000 microseconds * initial pulse duration : 0 usando o programa padrão do exemplo da aplicação estou com o seguinte problema * eu habilito a saída PWM como já descrito. * ajusto a largura do pulso para 100% - a válvula abre dando saída da água do meu processo. * mudo a largura para qualquer valor entre (100 a 80)% e nada muda na minha vazão que continua totalmente aberta. * mudo a largura para 79% ou menos e a válvula tranca. Ainda não tenho nenhuma razão para acreditar que o problema e na válvula ou na aplicação. Tem alguma ideia para eu testar, antes de desistir desse modulo da Siemens? Obrigado Alexandre Rufino - AETTeam Denilson Pegaia Hi, do you use the output from CPU or from signal board? Did you have already tired tochange the time basis from miliseconds to microseconds? --------------------------------------------------------------------------- Translation by moderator: Good morning, Mr. Denilson. I am having difficulty in modulating a PWM positioner valve using the S71200 with Signal Board with PQM signal (200 kHz). The device is to work with 200Hz, so I configured Siemens hardware as follows: * Signal type: PWM * Out source: signal board * Time base: microseconds * Pulse format: hundredths * Cycle time 5000 microseconds * Initial pulse duration: 0 Using the standard application example program I have the following problem * I enable PWM output as already described. * I adjust the pulse width to 100% - the valve opens giving water out of my process. * I change the width to any value between (100 to 80)% and nothing changes in my flow that remains fully open. * Changes the width to 79% or less and the valve locks. I still have no reason to believe that the problem is in the valve or the application. Do you have any ideas for me to test before I give up this Siemens module? Thank you Alexandre Rufino - AETTeam ------------------------------------------------------------------------------------------ Split from TIP for S7-1200 und PWM. Hi, The post is outdate, but i did have the same problem, the solution for me was change the format of pulse duration. (obs: I am using TIA portal V15.1, and the Cpu1214 DC/DC/DC). Signal type: PWM. Time base: Microseconds. Pulse duration Format: Ten Thousandths. and the chck box "Allow runtime modification of the cycle time" was selecionated. In the program, i write the two first bytes of the address, in my case start in 1008 and finishing in 1013, the Duration of the pulse is written int the qword 1008. The voltage change occur conformable de value is changed, my cycle time is the 8333 microseconds (120Hz), and i writte the value btween 0 and 8333 in the Qword 1008, and the voltage also change between 0.2V and 23V. It's necessaty verify the PIP image, i don't have certainly wich is the best choice, but slecionated the option "none" or "automatic update".
	Last edited by: Bruno_Bertotti_991 at: 07/16/2021 16:48:54
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