According to the present invention, there is provided a solenoid switch which includes a pair of fixed contacts spaced away from each other, a solenoid, a contact pressure applier, and a moving contact. The ribbon is electrically connected to the die and to the connection terminal, and has a prevalent dimension along a first axis, a width, measured along a second axis, which is transverse to the first axis, and a thickness, which is negligible with respect to the width; the ribbon moreover has a cross section that defines a concave geometrical shape. A web server is integrated in the field device, in a Plant Access Point or in the remote terminal; the web server provides all requested device information, which is the so called firmware, of the field device in the form of dynamically produced contents to the remote terminal. With the pressure-adjusting means the compression pressure can be adjusted with high precision, and due to the well-defined contact surfaces, which minimize the risk of vein stasis, the compression pressure is constant irrespective of any movement of the hand or forearm.