# VFD Remote Fwd - Rev Push Buttons



## ozengines (Oct 3, 2017)

I have worked out the speed control pot problem on the SAJ unit I asked for help on in a previous post.
I remotely mounted a Fwd, Stop, Rev push button to control my lathe. These push buttons are n/o contacts and looking at the VFD manual they are just a momentary close to activate each command, is the correct?
The problem I have is when I push either the fwd or rev buttons the motor runs but when I let go the button the motor stops. There must be another parameter that transfers the unit panel buttons to my remote buttons.
I can't find any help on these SAJ Drives


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## oliquir (Jan 13, 2011)

dont know if this is the vfd you have
http://viet-trung.com.vn/Data/upload/files/sach huong dan/SAJ 8000B.pdf


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## micromind (Aug 11, 2007)

Most digital inputs on VFDs need to be maintained contacts. 

One exception is if it's set up for 3 wire start-stop, the start button will be momentary.

The easiest way would be to use 2 two pole relays. One for FWD the other for REV. 

Use one pole of each relay for the digital input on the VFD and use the other pole as a latched contact with the pushbuttons. 

You'll need a separate power source for the pushbuttons and relay coils and be careful to keep this source apart from the VFD inputs.


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## Jeff B (Sep 30, 2017)

"Pulse" inputs to VFD's will allow starting from N.O. contact with push-button. Press "Start" push-button to start VFD, release push-button, and VFD continues to operate.

"Start" input may be configured as momentary using an external relay. Wire the coil to energize when the "Start" push-button is pressed and de-energize when the "Stop" push-button is pressed. The relay common and N.O. contacts would connect to VFD "common" and the "Start" input terminal.

When using both "Start" and "Stop" inputs on the VFD, the "Stop" input is to be configured as momentary and must controlled via N.C. contact and push-button so the input is removed when the push-button is pressed. This will also stop the drive if a wire is loose or disconnected. It is fail-safe. *Do not* use a N.O. contact on a "Stop" input configured as "Pulse".


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## ozengines (Oct 3, 2017)

I will look again this morning, the buttons on the VFD unit would only be momentary n/o so why wouldn't you be able to transfer to the same remote panel.?
Momentary for FWD & REV and the Stop is just a reset to off.
Back soon after I have another play.


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## John Valdes (May 17, 2007)

Pull out your manual the came with the control and take a look at the IO. And the program setting for the terminal board. (macro)

2 wire? 3 wire? and the other options/macros to allow you to customize the external IO to exactly what you want them to do.
The same diagram you used to wire up the remote buttons. You had to know where to land your control wires.

You should be able to do this without the use of any relays. The control has its own power supply. If the remote station is very far away, then you may need a relay or two.
The manual has all your answers with a schematic for each macro.

If you have no manual. Try to download the macro that you are using.


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