This equipment for planetary or pan concrete mixer makes possible to evaluate, in real time, viscosity of concrete like self compacting concrete. That is to say its workability or consistancy, data confimed during slump-flow test. VISCOPROBE includes two parts: First part is mechanical. It is made of a cast steel ball (probe) fitted inside the mixer on the rotating driving system. This tool dives into concrete and is driven in the same path as shovels during mixing (on which it has no effect). Measuring electronics - a force sensor with strain gauge - is protected in the upper part of the probe which never dips into concrete. It broadcasts measured signal through modem towards a PC which analyses and translate data. Should parameters be within permissible tolerances (comparison of threshold value and dynamic viscosity parameters to the values of reference batch), display turns to green, informing operator that SCC batch is in compliance and ready to be delivered. In contrary, a graph enables to get an indication on causes of errors that have led to non conforming workability : water proportioning, admix proportioning, quantity of fines. VISCOPROBE can thus be considered as a “super-wattmeter” which makes possible online control inside mixer transforming it into rheometer. This device enables to limit or even to avoid current tests made on concrete at transit mixer’s level.