The ZELIO range of programmable relays, part number SR 1**, first went on sale around the year 2000. Zelio Soft 1 software was used to program this range of relays. This range has been discontinued. 

The ZELIO 2 range part numbers SR2** (compact) and SR3** (modular) replaced the old SR1 range around 2005 and is still available. Zelio Soft 2 software is used to program this range of relays. 

It is not possible to use Zelio Soft 1 programming software to program SR2** and SR3** relays, or Zelio Soft2 to program SR1 relays.