Knowledge Base

The outputs on the XIRO16 are relays. You can wire these as you would any other relay contact. Six of the relays are SPST, and two are SPDT.

If you intend to use this board to switch 120/240VAC circuits, you must check that you are in compliance with all electrical safety regulation in your country. The board provides 6mm tracking distance between relay contacts and the electronics. All relays on a given connector should be switching the same line phase. Under no circumstances mix mains (power line) circuits with extra low voltage circuits on the same side of the board. Please see also our product disclaimer.

The diagram above shows 4 of the XIRO16 relays connected to various AC loads. The relays are shown in the de-activated (output OFF, no power to the board) position. The AC power source is shown as L for Line and N for Neutral. The voltage may be 24VAC or 240VAC or anything in between. However, you must observe the following rules:

  1. For voltages over 24VAC make sure you are complying with all local regulations concerning wiring of lethal voltages.
  2. Never, ever, use different supply voltages or mains phases on one group of relays. The relays show above constitute one group. The XBIO16 has two such groups of 4 relays.

The diagram shows three loads:

Coil

Output 2 is driving a coil. This could be a contactor or a solenoid valve. We have shown a resistor-capacitor snubbing network across the coil. It is generally assumed that for AC loads a resistive-capacitive snubber will reduce the damage due to arcing. In our experience with comprehensive tests of driving a large contactor, this is not necessarily true. We found the R-C snubber actually did more harm than good. There is some excellent material here on this and other relay related topics. The main reason for using a snubber on relay contacts is to suppress arcing and thereby extend the contact life. However, there is another reason, namely suppression of electromagnetic interference (EMI). Contactor coils in particular seem to generate a lot of EMI, sometimes enough to upset the SPLat processor and cause erratic behaviour. A small snubber comprising a 10nF 3kV ceramic capacitor in series with a 100Ohm 1W resistor will usually clean this up.

Incandescent lamp

Output 1 is driving a small incandescent light bulb. The thing to watch here is that a filament lamp can draw up to 20x is nominal current rating at turn-on. This inrush current can lead to early failure of the relay contacts. Allowing for this factor a 5A contact should not drive more than a 250mA lamp!

Small reversible AC motor

Outputs 0 and 6 are between them driving a small AC motor of the type that has 3 connection wires to allow it to be driven in both directions. Output 6 is a SPDT (single pole change-over) relay connected to feed one or the other side of the motor. Relay 0 switches the main power to relay 6, for on/off control.