What are the rules for PROFINET device names in PROFINET specification V2.3 in STEP 7 V5 und TIA Portal?

1. The device name must not be longer than 240 characters. The following characters are permitted:
   • Lower-case letters "a" to "z"
   • Numbers "0" to "9"
   • Hyphen or period

2. One name component in the device name - a character string between two periods - may not be longer than 63 characters.

3. The device name may not begin or end with a hyphen.

4. The device name may not begin with the character string "port-xyz" (x, y, z = 0 to 9).

5. The device name must not have the form of an IP address n.n.n.n (n = 0 to 255).

Rules in STEP 7 V5 and TIA Portal
To be able to communicate with PROFINET devices they have to be assigned names. These names are the device names in the Hardware Configuration. The device name must comply with the standard 61158-6-10. For this purpose it is necessary to observe the above mentioned rules.

The rules to be followed in TIA Portal can be found in the manual in Entry ID 109773506.
If you use the "Generate PROFINET device name automatically" option in the hardware configuration in TIA Portal, then the generated PROFINET device name will comply with the standard.
In TIA Portal, the PROFINET device name is converted automatically if invalid characters including uppercase letters are used. If the converted name is not differ from the name of the module, then the name of the module must meet the required rules. 

The rules to be followed in STEP 7 V5 can be found in the manual in Entry ID 109751824.
In STEP 7 V5 you may use uppercase letters in the PROFINET device name. The PROFINET device name is transferred to the PROFINET IO device as created by the user. Therefore PROFINET device names with uppercase letters are also transferred to the PROFINET IO devices. SIEMENS PROFINET devices also support uppercase letters in the PROFINET device names. However, you should note here that devices of other manufacturers do not support this.