XS2 Dout to +bat?

Forrest 5 years ago in Expansion modules / XA2, XS2 updated by Gustav Widén (System support) 5 years ago 4

I'd like to have IQAN control be paralleled with switch control. This specific application will be a drop axle. I want the IQAN to drop the axle in certain situations, and have a switch that will drop it at any time, even if the control system is powered down,

I believe I have to protect the module from back-feeding, correct? Will just diode protection be enough or do I need to have the Dout controlling a relay that would toggle the input between the switch and a +bat source?


Hi Forrest,

I've implemented controls like this before.  Yes, you do need to use a diode between the DOUT and the actuator, to prevent back-feeding. The anode of the diode should attach to the DOUT, with the cathode attached to the actuator.  One side of the switch should attach to the cathode of the diode too, with the other terminal going to the power source.  This is called a wired-OR.

One thing to be aware of, is that the diode will introduce a voltage drop of 1.5-2.0 volts when the DOUT is powering the actuator.  This can cause problems if the voltage required to positively activate the actuator is low(e.g. actuator requires a minimum of 20 volts to actuate), and/or when the power to the XS2 is lower than normal (low battery).  The only way to avoid this, is to use a relay as you described.

Hi Forrest,

Adding to Mark's comments, there is information in the XS2 instruction book regarding using a switch in parallel with an IQAN module.  If you look in the section discussing the Digital Outputs there is a diagram showing the basics of the setup.

ah. I had looked at the clamping diodes in the past, but didn't notice or remember that part. I had also looked at the failure modes in the appendix, but it didn't mention the Douts.