Logging individual bits of a variable with data type "word" logs incorrect values.

A word consists of 2 bytes. When reading an individual bit of a word, Siemens PLCs apply the byte order "big endian": first the higher byte, then the lower byte. Effectively this means that a byte swap is applied and that when you are requesting a bit value from the 2nd byte, you are actually getting the value from the 1st byte and vice versa.

For example: Let's say we have a word at address 20. That word spans from address 20.0 to 20.7 (8 bits, byte #1) and from 21.0 to 21.7 (8 bits, byte #2). If bit 20.0 is read by the edge gateway, you're actually getting the value from address 21.0 back. If you're reading bit 21.2, you're actually getting the value from address 20.2.

Additional notes:

• This cannot be turned off in the PLC settings.
• When viewing the word value in TIA Portal itself, in binary, it is shown as normal.

There are several solutions:

1. In the PLC project, apply a manual byte swap to the variable to counteract the above.
2. In the PLC project, use data type Byte instead of Word.
3. In the IXON Cloud, swap the addresses. Note that this may result in user errors in the future, because the addresses technically no longer match the addresses shown in the PLC project.