In the Profinet network, consisting of a CPU and distributed IO modules, during network configuration, we not only assign an IP address to the distributed IO modules but also allocate a device name. Why is this necessary, and what role does the device name play? Let's first compare Profibus DP and Profinet networks.
In the Profibus-DP network, distributed IO modules do not have device names; they only have a Profibus-DP address. Each distributed IO module has DIP switches used to set the address. For example, setting the CPU's address to 2 and the ET200S address to 38 (both in hardware configuration and DIP switches). After downloading the hardware configuration to the CPU, the CPU starts calling out, "Address 38, Address 38." The ET200S, recognizing its DIP switch set to 38, responds, "It's me, I am Address 38." The CPU acknowledges, "Oh, it's you. Come, let's get to work."
However, this method doesn't work well in the Profinet network. Since Profinet's distributed IO lacks DIP switches, when the CPU calls out, "Address 38, Address 38," the ET200S might think, "Is it calling me? I am not Address 38." Ignoring the CPU, the ET200S doesn't respond. After shouting for a while with no reply, the CPU, exhausted, lights up the SF and BF lights, indicating, "Oops, I can't find ET200S."
Alright, the network has changed, and we need to make new connections. In accordance with the IEC 61158-6-10 standard, to ensure proper communication between Profinet devices, it's necessary to assign specific device names (device name) to each device (CPU, IO module). Therefore, when configuring Profinet, there is an option for "Device Name." In TIA Portal V13, locate the respective IO module in "Device View," click on "Properties," then "Profinet Interface X1," and finally "Ethernet Address." Dragging the slider in the right window reveals the following image:
The system can automatically generate device names, but you can also modify them manually. When we download the hardware configuration with assigned device names to the CPU, the CPU starts calling, "Wukong, Wukong." The ET200S, thinking, "Who is Wukong? I am the Monkey King," continues to ignore the CPU.
Why does this happen? Although we downloaded the hardware configuration to the CPU, we haven't given a name to the ET200S from the hardware perspective. So, it only recognizes itself as the Monkey King. At this point, we need to issue the next command, giving our monkey friend a new name.
Connect the PC to the Profinet network, click on "Online Access," locate your network adapter, and double-click "Update Accessible Devices":
Click on the found IO module, then on the right side, click "Assign Name," and give the ET200S a name (Wukong):
With the proclamation of the decree, ET200S now understands that it is indeed "Wukong." The CPU continues to call, "Wukong, Wukong." ET200S responds, "Master, I'm here." The CPU says, "You mischievous monkey, I'm hungry." Wukong: ...