Modbus communications not working ? How do you know what’s wrong – is it the baud rate, the parity or even the address? There are so many things that can affect communications.
The Modbus protocol does not support discovery. There is no broadcast message that you can send that will make a slave respond with its port and address settings. The protocol allows for broadcast messages to be sent but doesn’t demand that every vendor supports this feature.
Use the CAS Modbus Explorer to find the correct port settings and the correct slave address.
The tool automates the process of trying all the combinations and reports the results. We provide burst and standard mode. In burst mode we send messages to all the possible slave address before waiting for a reply from any of them. This dramatically improves the time required to do the discovery.
The tool works for RS232 and RS485 by allowing you to search for a single device or multiple slaves. To connect to a RS485 network from your laptop you simply need a USB-to-485 converter.
Here is the problem – there are thousands of combinations:
Baud 300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200 Parity, None, Odd, Even Stop Bits 1, 2 Data Bits 7, 8 Address 1-254
If you had to manually search/test all these combinations it will take you ages. Relax, go for lunch and let the CAS Modbus Explorer do all the work for you.