Hi,

My train set uses a potentiometer wired as a variable voltage divider to control the speed of the train. The voltage range is from 0 to 26 VDC. I was wondering if there was any way that I could use a PLC to control the speed of the train. The PLC I have is a Micrologix 1000. It does not have any analog outputs or else I would use those. I was possibly thinking of using a digital potentiometer but I am not sure if that would work. Any help would be appreciated. Thanks.


Ryan

 

What do you intend to achieve with a PLC?
Even if it had a analogue module?
Not sure what current train controllers are, maybe PWM?
I have an old SCR design by GE for a Model RR speed controller with rev. capability..
Max.

 

While 0 to 26 VDC is nice to know you need to know the current the train requires. The reason a potentiometer was used is likely because it was the simple solution. Per Max you could look at maybe a PWM solution or SCR solution but why?

Ron

 

This is page 1 of the RR controller.
Or..http://www.electronicsinfoline.com/pin/24575/
Max.

 

PLC without modules is just power supply and processor. Without modules it is very expansive piece of scrap.

 

What do you intend to achieve with a PLC?
Even if it had a analogue module?
Not sure what current train controllers are, maybe PWM?
I have an old SCR design by GE for a Model RR speed controller with rev. capability..
Max.

I am trying to automate my trains to go around the track and perform other tasks by themselves and without me needing to flip switches. My trains require 0.7A of current according to my original controller.

 

If you want to use automation, then a Smart Relay is one possible answer, small version of a PLC, they have a real time clock that could provide schedules etc, for accel control a ramp up into a SCR type control could be used.
Max.

 

Is there any way that I could do this with the PLC? I was able to get one from work to use and I really don't want to have to buy anything else for this project being that it is just something for me to tinker around with. Thanks

 

The Micrologix just comes with digital output, not sure if they have an analogue module as an add on.
The logic side will be OK for automating switching however.
But you would need integration of the speed controller which would be external to the PLC even if a analogue module Was available..
Max.

 

Thanks for the help. The micrologix 1000 does not have the ability to be added on to.

 

Page 5-3 of the manual does mention a single analog out channel. You can have 0 to 10 V or 4 to 20 mA and that looks to be about it as to analog out.

The analog input channels are single–ended (unipolar) circuits and can be individually enabled or disabled. The default is all input channels enabled. The two voltage inputs accept ±10.5V dc, and the two current inputs accept ±21 mA. The analog output channel is also a single–ended circuit. You can configure either voltage (0V dc to +10V dc) or current (+4 to +20 mA) output operation. The default is voltage output. The output must be configured for either voltage or current, not both. This is determined by the output configuration. When in the Run mode and the output is configured for voltage, the voltage output terminal is active and the current output terminal is inactive. Similarly, when in the Run mode and the output is configured for current, the current output terminal is active and the voltage output terminal is inactive. When the system is not in Run mode, both the voltage and current outputs are inactive.

Ron

 

That is for the Micrologix 1000 with the analog option. Mine does not have that just discrete in and out.