Any non-zero value to a BI is interpreted as TRUE (1). The OR operator will return TRUE is ANY of the values is TRUE. The AND operator will return TRUE only if ALL the values are TRUE. The XOR operator will return TRUE if there are an ODD number of TRUE inputs. The logical not operations (NAND, NOR, NXOR) will simply return the opposite of what the normal function would. And of course, the packed operators (___X) will perform the selected functions on a bit-by-bit basis. -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Hicks, David Sent: Wednesday, August 08, 2012 10:43 AM To: foxboro@xxxxxxxxxxxxx Subject: Re: [foxboro] Question about OR usage in CALC function block logic As far as I know the "OR" function is a Boolean instruction and only recognizes a 0 or 1. Anything other than a 1 in RI01 location will result in BO01=FALSE according to the conditions that you have provided. -----Original Message----- From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On Behalf Of Quay B. Finefrock Sent: Tuesday, August 07, 2012 7:25 PM To: foxboro@xxxxxxxxxxxxx Subject: [foxboro] Question about OR usage in CALC function block logic Good day ladies and gents, What happens in a CALC function block when an OR function is used with a stack that includes a real value. For example, what is written out to BO01 in the following case? IN BI01; = False IN RI01; = 13.0 IN BI02; = False IN BI03; = False OR; OUT BO01 = ? Does this produce an error? Does the result depend on the value of RI01? I am reverse-engineering some old I/A logic and I do not have access to a simulator to test and see what will happen in this situation. Can someone please help me out? Regards, Quay -- Quay B. Finefrock PSD Controls Pte. Ltd. Phone: +65 9327 2923 (Singapore) +673 883 1480 (Brunei) +60 17 820 6900 (Malaysia) Email: Quay@xxxxxxxxxxxxxxxx _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave *** Confidentiality Notice: This e-mail, including any associated or attached files, is intended solely for the individual or entity to which it is addressed. This e-mail is confidential and may well also be legally privileged. If you have received it in error, you are on notice of its status. Please notify the sender immediately by reply e-mail and then delete this message from your system. 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For a list of European legal entities within the Invensys Group, please go to http://www.invensys.com/en/legal/default.aspx. You may contact Invensys plc on +44 (0)20 3155 1200 or e-mail reception@xxxxxxxxxxxxx This e-mail and any attachments thereto may be subject to the terms of any agreements between Invensys (and/or its subsidiaries and affiliates) and the recipient (and/or its subsidiaries and affiliates). _______________________________________________________________________ This mailing list is neither sponsored nor endorsed by Invensys Process Systems (formerly The Foxboro Company). Use the info you obtain here at your own risks. Read http://www.thecassandraproject.org/disclaimer.html foxboro mailing list: //www.freelists.org/list/foxboro to subscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=join to unsubscribe: mailto:foxboro-request@xxxxxxxxxxxxx?subject=leave