Calculation method of Siemens 840D PLC user alarm code

1. The calculation method of Siemens 840DPLC user alarm number is as follows:

The user alarm starts from 700000 because it corresponds to DB2.DBX180.0. You can quickly find the alarm point in the DB data block through the following methods.

180 (initial alarm point) + (middle two digits multiplied by 8) + (quotient of the last two digits divided by 8 + decimal point + remainder)

Example: Alarm number 701661

180 (initial alarm point) + 16*8 (multiply the middle two digits by 8, octal algorithm) + 61/8 (the last two digits divided by 8 = quotient plus decimal point + remainder, for example, this is the quotient of 7 with a remainder of 5 )=180+128+7.5=315.5, so the alarm bit of 701661 is DB2.DBX315.5.



2. Siemens 828D provides 248 PLC user alarms

(700000 – 700247), the corresponding interface signals are DB1600.DBX0.0-DB1600.DBX30.7.