A support and control device for circular knitting machines, destined to be mounted in a circular knitting machine equipped with at least one supporting structure, with at least one component-holding unit rotating around a central axis of rotation, and with a plurality of stitch formation components movably associated with the component-holding unit, the device comprising at least one support body provided with: - a mounting portion configured for allowing the device to be mounted to the supporting structure of the circular knitting machine; - a front side facing said component-holding unit of the knitting machine and provided with at least one cam for controlling at least a part of said plurality of stitch formation components, said at least one cam defining a guiding path configured for interacting with respective butts for controlling each of the stitch formation components of said at least a part of said plurality of stitch formation components; - a rear side, opposed to said front side and facing the outside of the knitting machine, away from said component-holding unit; wherein the device comprises at least one through opening between said front side and said rear side, open both on said front side and said rear side, and open on at least one portion of said guiding path; wherein said through opening defines an empty space placing at least a portion of said guiding path of said at least one cam in direct communication with the outside of the device, at least in an operating configuration of the device, so that the respective butts of the stitch formation components interacting with the cam face and are in direct communication with said empty space; the device being characterized in that the support body of the device has a thickness, calculated as size in a direction from the front side to the rear side, and wherein the device comprises a first side face and a second side face, which are transversal to and structurally connect said front side and said rear side; and wherein said cam is defined on a cam body removably mountable to the support body of the device, so that the guiding path is defined on said front side, and wherein said cam body comprises a front portion on which said guiding path is defined, and a fastening portion placed laterally to said front portion and provided with means for fastening the cam body to said first side face or said second side face of the support body of the device. the device comprising at least one support body provided with: - a mounting portion configured for allowing the device to be mounted to the supporting structure of the circular knitting machine; - a front side facing said component-holding unit of the knitting machine and provided with at least one cam for controlling at least a part of said plurality of stitch formation components, said at least one cam defining a guiding path configured for interacting with respective butts for controlling each of the stitch formation components of said at least a part of said plurality of stitch formation components; - a rear side, opposed to said front side and facing the outside of the knitting machine, away from said component-holding unit; - a mounting portion configured for allowing the device to be mounted to the supporting structure of the circular knitting machine; - a front side facing said component-holding unit of the knitting machine and provided with at least one cam for controlling at least a part of said plurality of stitch formation components, said at least one cam defining a guiding path configured for interacting with respective butts for controlling each of the stitch formation components of said at least a part of said plurality of stitch formation components; - a rear side, opposed to said front side and facing the outside of the knitting machine, away from said component-holding unit; wherein the device comprises at least one through opening between said front side and said rear side, open both on said front side and said rear side, and open on at least one portion of said guiding path; wherein said through opening defines an empty space placing at least a portion of said guiding path of said at least one cam in direct communication with the outside of the device, at least in an operating configuration of the device, so that the respective butts of the stitch formation components interacting with the cam face and are in direct communication with said empty space; the device being characterized in that the support body of the device has a thickness, calculated as size in a direction from the front side to the rear side, and wherein the device comprises a first side face and a second side face, which are transversal to and structurally connect said front side and said rear side; and wherein said cam is defined on a cam body removably mountable to the support body of the device, so that the guiding path is defined on said front side, and wherein said cam body comprises a front portion on which said guiding path is defined, and a fastening portion placed laterally to said front portion and provided with means for fastening the cam body to said first side face or said second side face of the support body of the device.