PWM Instruction

[VKC 0]

Somebody has experiance wth PWM (PWM_M) instruction? I test it with GX Developer 8.24a, GXIEC Developer 7.00, GXIEC Developer 7.04. Tested on GX Simulator. Realy tested on FX1N, FX2NC, FX3U. Does not works. My colegues in company made same tests. Does not works. Some advice please?

[KAZAH 6]

instruction on the simulator does not work.only on the controller.

[Crossbow 295]

When you start the simulator, there is a method to see a list of the commands which cannot be simulated. Also, PWM_M is a GX IEC Developer command, so how did you test it in GX Developer?

[katmandoo tortoise 0]

Well, the original message said PWM (PWM_M) so I would read that as the PWM command, and PWM_M in GX IEC. The simulator does not replicate the instruction, but it has also been tested really on FX PLCs (so the message says). The instruction works, I have used it many times. My guess is that it is not being applied correctly. The instruction will only work with one of the two high speed outputs (Y0 or Y1) so trying to use it on any other output won't work. It can only reasonably be used on a transistor output, since a relay output will have to be driven slowly, and the relay will eventually fail being pulsed on and off so many times. That said, the PWM instruction *will* work with a relay output, but you must set the times long enough for the relay to operate. The first operand is the ON time in mS and the second is the total period, also in mS. So: PWM K500 K1000 Y0 will operate Y0 with a 1 second cycle, the relay being on for half of the time and off for the other half. The second operand must not be less than the first, otherwise the cycle can't work. On a relay output PLC, this will make the PLC tick like a clock! In what way is the "not working" being exhibited? Hope this helps

[WKla 0]

Hello, Just struggling with the same instruction. I want to activate the output Y0 or Y1 for a period of 8-500ms. But I want to activate it for only one pulse. Then to start it again when need it. Who could I reset the activation bit when the pulse is done? I have tried with - LDF Y0: is working on FX3G (4.1ms scan time), but on FX1N (16ms scan time) doesn't reset the bit. - LDF M8340 - is not working on any PLC - "Activation bit set" and "Y0 not activated" then reset the activation bit - this method works well on FX1N, but I don't know if it works in any situation of scan time etc. A safe method is to start a ms timer with the variable time of "lenght of PWM pulse"+constant (scan time perhaps), but that complicates the program. Thank you.