In this instrument system having at least one instrument disposed in a housing (1) the housing is to be mounted detachably on a support (3) and the customer himself is to set a coding for each system module comprising instrument and support. Grooves (23 or 27) are provided in the support (3) for taking up coding pins (31). In the assembled state the grooves (23) of the support form groove pairs with the grooves (27). The inner spaces of the grooves of a groove pair together form an interstice for accommodating just one coding pin (31). This is fixed in either the groove (27) or in the groove (23). In this way the assignment of a housing (1) to a support (3) is established through the positions of the coding pins (31).
