A pneumatic convertible relay capable of performing logic functions has a relay body that includes a control mechanism for moving a valve member. The valve member includes a slideable stem with a foot on one end and a head on the other end. For a normally open construction the head carries an angular valve head seal and in normally closed construction the foot also carries a seal for controlling flow between a mating seat and a passage along the slidable stem. The valve body is in three sections and includes an inlet, an outlet, an exhaust, and two control openings. The control mechanism includes a diaphragm positioned to act on the foot of the valve member under control of pressure applied to either of the control openings. A slideable shuttle provides alternative operation. The valve is convertible from a normally open construction to a normally closed construction by changing the position of a passage in a valve seat to connect either the inlet to the outlet or the exhaust to the outlet and the position of the annular valve seal, while the other components remain the same. This invention relates to improvements in pneumatic relays with logic functions. There are many types of pneumatic relays known in the art which allow for various combinations or sequences of control. These relays may be generally classified in two categories. One category of prior art relays are those capable of performing logic functions according to their mode of connection to various control openings. These relays allow the construction of predetermined automatic controls with the help of a reduced number of relays. However, these relays are relatively complicated and complex as well as expensive. Another type of relay is that capable of performing only one basic logic function. These relays are of relatively simple construction and low cost; however, allow only one logic function to be accomplished, e.g., the inhibit function. The association of these relays, according to the rules of Boolian algebra allows several complex logical functions to be performed. In order to simplify the construction of a network to provide a desired logic function and reduce the cost of it, it is preferable to use only two elementary cells or relays. One, normally open (n/o) corresponds to a negation or inhibit function. The other, normally closed (n/c) corresponds to an affirmative function. Of course, normally open relays as well as normally closed relays are known in the art. However, these known relays have very different functions, and cannot be constructed form identical elements. This invention provides a pneumatic relay capable of being constructed from identical components which may take the form of either normally open or normally closed with minor variations. The relay, in accordance with this invention, allows provision of all the logic functions and the construction of a hazard free memory. Consequently, this invention relates to a pneumatic relay with logic functions characterized in that, inside the relay''s body, it includes a control assembly with at least two access openings. A valve slide member has a foot On one end and a head on the other end provided with a valve seal, and the valve member is guided in the valve body. A passage extends in the valve body along the stem of the slideable valve member, and the valve seal on the valve head controls the communication between an inlet chamber and this passage, which may be in the form of a groove in the stem of the valve member. In a normally closed construction, an outlet port is in communication with the groove passage in the valve stem, and the valve head seal closes this passage from the inlet chamber in normal condition. In the normally open construction, a passage is provided in the valve seat, normally connecting the inlet and outlet chambers, while the groove passage in the stem of the valve member is normally connected only to exhaust, but when the control mechanism changes the position of the valve, the valve head closes the passage between the inlet and outlet chambers, and connects the outlet chamber to exhaust through the groove in the valve stem.