Later this year, all newly-registered vehicles will be equipped with a version 2 second-generation smart tachograph (G2V2). Soon, the replacement of tachographs will be mandatory also in older vehicles operating in international transport 
Currently, vehicles are fitted with gen 1 smart tachographs, but from this August it will be mandatory to install version 2 second-generation smart tachograph (G2V2).
G2V2 tachograph is equipped with a GNSS tracker and requires the use of the OSNMA service to authorize the GNSS position recorded by the tachograph 
At the moment, OSNMA is not available yet and for this reason, the European Commission decided to launch 'transitional tachographs'.
More about the topic you can find in INELO article 