Modular Gateway
The assignment of data exchange is somewhat mysterious. Is there an example available?
Up to 512 bytes are transferred in the little endian format between two gateway modules. Output data and input data are shared between the gateway components.
Modbus TCP | Profibus |
|---|---|
FC 0x03 Read Holding Register 1 - 122 | Output offset 0 - 244 bytes |
FC 0x10 Write Multiple Registers 1025 - 1147 | Input offset 0 - 244 bytes |
Have in mind that Modbus registers per definition use 16 bits or two bytes.
Profibus is able to use 244 bytes for input/output in each direction.
Therefore just 122 registers are useable for the access of the 244 bytes.
Can I use RS232 to Ethernet/IP?
Yes, you can to it with the following components:
modular Gateway Serial https://www.kunbus.com/serial-rx-gateway-module.html for rs232
modular Gateway Ethernet IP https://www.kunbus.com/ethernet-ip-gateway-module.html
Scripter RevPi Gate Seriell https://revolutionpi.de/tutorials/downloads/#revpiimages
Do I need 3 gateways each on Profinet to integrate 3 Modbus-TCP participants into the system or is one gateway sufficient?
All modular gateway modules act as slave.
Therefore three Modbus TCP masters would then access one slave together.
From a purely technical point of view a common access is possible considering that the process data 512 bytes each for input and output direction are sufficient.
Furthermore it has to be considered that the Modbus TCP masters then also write into different registers.