Logix5000 Controllers General Instructions - SLAC Confluence

Compare Instructions (CMP, EQU, GEQ, GRT, LEQ, LES, LIM, MEQ, NEQ) 211Use Strings In an ExpressionUse a relay ladder or structured text expression to compare string datatypes. To use strings in an expression, follow these guidelines:• An expression lets you compare two string tags.• You cannot enter ASCII characters directly into the expression.• Only the following operators are permittedOperatorDescription= equal< less than greater than>= greater than or equal not equal• Strings are equal if their characters match.• ASCII characters are case sensitive. Upper case “A” ($41) is notequal to lower case “a” ($61).• The hexadecimal values of the characters determine if one stringis less than or greater than another string. For the hex code of acharacter, see the back cover of this manual.• When the two strings are sorted as in a telephone directory, theorder of the strings determines which one is greater.ASCII CharactersHex Codes1ab $31$61$62lessergreater1b $31$62A $41AB $41$42B $42a $61AB < Ba > Bab $61$62Publication 1756-RM003I-EN-P - January 2007