Art*lantis
Art*lantis R versions 1.0.2 and later come complete with Piranesi support.
In Art*lantis R, use Inspector > Render and select Piranesi as the 'Save as type' or Format. Or use Render > Render Fixed Cameras and under Doc. format, select EPix (Piranesi). Then click on Options and choose the width and height for your EPix file, and any other settings for the quality you require.
Then use Render Now. This will create an EPix file that you can open in Piranesi.
Please note: Art*lantis's patch release v2.0.3 fixes an error where no depth channel was being created on EPix export. Art*lantis 2 customers are recommended to install this patch.