5. Programming on the device5.3 Circuit diagram elements5.3.5 Markers and analog operandsThe term "marker" is used to represent marker bits (M). Marker bits (M) are used tostore the Boolean states 0 or 1. A marker bit is also called an auxiliary relay.easyE4 devices also manage the marker bits in marker bytes (MB), marker words(MW) and in marker double words (MD). A marker byte consists of 8 marker bits, amarker word of 16 marker bits and a marker double word of 32 marker bits.You can use a specific bit and, accordingly, a specific byte to save a contact's state. Forexample, marker bit 9 is also found in market byte 2, marker word 1, and marker doubleword 1. You can use the following conversion table to figure out which word contains abit or which bits encompass a specific double word.Bear in mind that after the division, a rounding up to the next higher integer is neces-sary, even if the decimal number is below 0.5.Searched for GivenBitM nByteMB nWordMW nDouble WordDW nBit (M) 8n-7 to 8n 16n-15 to 16n 32n-31up to 32nByte (MB) n82n-1to 2n4n-3to 4nWord (MW) n16n22n-1to 2nDouble word (DW) n32n4n2n = 1 to 96Table 56: Conversion table M, MB, MW, DWExample 1: given Bit81 =M81; n=81;l Byte(MB) = n/8 = 10.125 ≈ 11l Word(MW) = n/16 = 5.0625 ≈ 6l Double word(DW) = n/32=2.5313 ≈3Bit81 is contained in MB11, MW6 and DW3.Example 2: given Byte21=MB21; n=21;l Bit(M) = 8n-7 to 8n = Bit161 to 168l Word(MW) = n/2 = 10.5 ≈ 11l Double word(DW) = n/4 = 5.25 ≈ 6Byte21 contains the bits Bit161 to Bit168. Byte21 is contained in MW11 and DW6.Marker bit (M), marker bytes (MB), marker words (MW) and marker double words(MD) are used in the circuit and function block diagram.Avoid any accidental double assignment of markers. In this way, you can assign theavailable 96 or 128 marker bit contacts and also change the state of these marker bitseasyE4 11/18 MN050009 EN www.eaton.com 131
