The part number of the cable required to connect a PC running Zelio Soft programming software to the USB communication port on an SR2 or SR3 programmable relay is SR2USB01.
The communication lead SR2USB01 is 3m long and has a USB connector on one end and a dedicated Zelio connector on the other. You can find the datasheet for this on the web page for the product, here: https://www.se.com/uk/en/product/SR2USB01/usb-pc-connecting-cable-for-smart-relay-zelio-logic-3-m/