On Sat, 16 Mar 2013, Marco Patzer wrote:

> On 2013–03–16 Thomas A. Schmitz wrote:
>
>> \setupMPvariables
>>     [mycircle]
>>     [diameter=\Circlediameter,
>> ]
>
> MPvariables are local to a particular MP graphic. I need a way to
> set the variables global to all MPgraphics of that MP instance.

See the visualcounter module for an alternative way to pass values from 
TeX to MP. Basically, I define a namespace and then just access the 
parameters at MP end using

somvar := \....parameter{...};

etc.

Aditya