The present invention relates to service and maintenance solutions for programmable and/or reconfigurable modules (CM1, . . . , CMn), which are included in the nodes of a communications network (140). The module (CM1) contains a first digital storage unit (M1), which holds information pertaining to the accomplishment of a primary function of the module. A secondary function of the module involves control of the primary function. The module has an optical bi-directional interface (Iw) towards the first digital storage unit. Data in the first digital storage unit may be read out (D0) and may also be updated (Di) by the portable software carrier unit via the optical bi-directional interface. Data read-out as well as data updating may be accomplished independently of the primary function. Preferably, an access module (A) controls the bi-directional interface in response to an authorization signal (SA) from an authorization unit (120, 121, 122, 123).