Old thread, but that boiler doesn't appear to have EMS. Worcester Bosch at current time tend to use EMS, EMS+ and EMS2
Here's the installation manual for a Greenstar Ri (though maybe not yours) and you can see lack of EMS on page 36. The terminals are sometimes labelled BB instead of EMS.
I...
Forgot to mention... specific model of Tado V3 (but not Tado-X) support EMS1 (but not EMS+ or EMS2) directly with no converter.
A lot of the early V3's sold in UK don't have the EMS interface as UK plumbers just wire as on/off switch even if OT is available.
Later UK V3's do have EMS/OT
All EU...
@DerekPCB , sorry I'm a little late to this conversation, but maybe I have useful info for you, or other late comers.
First off, there there are a few very similar looking versions of this boiler around with similar names.
None that I'm aware of directly support OpenTherm as Worcester Bosch...