ProXR Relay Not Closing More Than 3 Relays

We are using the CONTROLLER, ETHERNET INDUSTRIAL RELAY, 24-CHANN SPDT +8-CHANN ADC card. When using the sample software (C#) to close relays, we are able to only close 3 relays. As soon as we try to close a 4th relay, the card freezes and disconnects from the network. Can I say it is a bad card or what would I look at to determine if the card is good and it is something else. I am software so I need step by step to help me if it is a hardware issue. Thank you.

Hi Mike,

The easiest way to determine if it’s a hardware or software issue is to use Base Station (Start - to test the functionality. You can find a guide for using this software at: Base Station Quick Start Guide -, but it’s relatively straightforward.

The most likely culprit if it is hardware is a bad power supply that doesn’t provide enough amperage to drive the multiple relays on top of the processory and ethernet module. This can cause a brown-out state and a comms failures. It can make it look like the hardware just reboots.

What is the power supply being used to power the relay controller?

Are the relays actually switching anything? If so are they switching inductive loads (motors, pumps, electromagnets)?

Hi Jacob, this came from my electrical person. Does this help?

Relay Module Current Draw (@12VDC Input)

  • as measured 250mA
  • from their spec 260mA max (Stand-by + Ethernet module)
  • additional 60mA max per relay
  • total of ~500mA with 4 relays ON

SIP DC-DC converter can output up to 5A @ 12VDC. Let’s just say 4A for 40C temperature derating.

Question now is how much current is the SIP DC-DC power supply drawing when it was loading up to 500mA, and if that was in excess of the capacity of external power supply (LAMBDA LQD-420) we were using.

I will try to guestimate:

  • with 9A max for the DC-DC converter input, and output load of about 12% (0.5 of 4A) of full load, and assuming an efficiency of 85%…the DC-DC converter is drawing about 1.27A (in excess of its 0.7A capacity)

So I think it’s a safe bet that we were overloading the external power supply. I don’t think we need to provide our info regarding that.

Other Questions:

  • (for NCD) Would brown out issue cause that to kill our Ethernet module.
  • I think we have headroom for the actual TE 15V power supply but we should know how many of the relays we turn on at the same time.

Hi Mike,

A brownout issue will reboot the Ethernet module causing a loss of socket. It could kill the ethernet module if done enough, but i’ve never see this.

It sounds like the power source of your primary power source (LQD-421) isn’t providing enough amperage to provide power for everything downstream if I’m reading this correctly. You might try simplifying the power source to a 12VDC 1.5 amp power supply.

Did Base Station show this same failure when being used to switch the relays?

Yes, the Base Station showed the same failure. We are going to look at another relay we have and see if it has the same issue. I will pass on your recommendation to them and get back to you when they have completed checking the other relay.