FEC920: USER GUIDEAppendix BPage 219September 18B3 FUNCTION BLOCK DETAILSB3.1 Eight Input OR BlockAn eight input logical OR block whose output is high (1, On) if any one or more inputs is high (1, On). If morethan eight inputs are required, a second block is automatically introduced, as shown in Figure B.2. The blocksin the figure are given the names ‘A’ and ‘B’, where ‘A’ and ‘B’ can be any of the 12 available instances.Figure B.2 Eight input OR blockOR blocks are used automatically by the ‘user wiring’ when more than one source is wired to the samedestination parameter. For example, it may be required that Relay (Digital I/O 2A2B) is to operate if channel 1alarm 1 and/or channel 2 alarm 1 channels goes active. In such a case, the ‘Active’ parameter for the twochannel alarms would be wired to the same relay’s ‘PV’ parameter.OR blocks are invisible to the user interface, but the iTools graphical wiring page for this configuration (FigureB.3), shows that an OR block has been introduced to OR the two alarm outputs together.Figure B.3 iTools representation of OR block usageA5E45696052A Rev-AA
