Modbus RTU Address changing through RS-485 communication.

Dear Experts.
Is it possible to change Modbus RTU Address through any third party software like modscan 32. we are ready to pay for the support.

I have 52 modbus devices in my project. all have modus address of "1". i can communicate these devices through modscan32. I don't have any support from actual supplier of the unit.
 
If you want to put them on a multidrop network and poll them one at a time, then each will require a unique slave node ID number.

Sometimes the slave node address is changed with a physical DIP or rotary switch, or jumpers. Other times the slave node ID number is configured in a firmware setup that uses a utility program to access the setup parameters. I have seen some Modbus-RTU-only field instruments that have a register for the slave node ID where one accesses the instrument on the default node ID, then write a new value to the slave node ID register, cycle the power and presto, the device now has the non-default slave node ID.

So, check the Modbus register map for your device for the serial comm settings and you might find that there is a register for the slave node ID. Presumably the default slave node ID is 1. Use Modscan to write a different value to the slave node ID register.

It would be prudent to get some stainless tags engraved with the various slave node ID number and tie the tag to the device as you make the change, because all those gizmos look alike and once you get distracted by whatever, remembering which one is which will be a challenge. Adding the baud rate and parity might be a good idea, too, if this device sets those up in the same fashion.

You are likely to need to cycle the power after changing the slave node ID number.
 
The Air2O Controls is yet another nominee for the Modbus Hall of Shame - a Modbus RTU implementation with non-configurable slave node ID.

There is no published register for the slave node ID.

No, there is no magic 3rd party software that does what the manufacturer has failed to implement.

As a work-around, if the Modbus Master/Client has Modbus/TCP (Ethernet) functionality, then you could use an Ethernet/RS-485 gateway (a serial server model with Modbus firmware) with each unit, where the IP address of the Ethernet side of the gateway becomes the slave unit identifier.

Maybe someone else has an alternative work-around.
 
The Air2O main control board has a LCD screen and keys to navigate the menu system. This would seem like the expected location to set the Modbus slave ID. Is there a parameter on the LCD screen for the Modbus slave ID?
 
If you cannot change the Modbus Address your only solution would be to use a Modbus TCP/IP to Modbus Gateway for each device. There are also Modbus TCP/IP to Modbus Gateways with multiple serial ports. Typically in a Gateway you can configure routing in the device to point to a specific device as an example a Modbus TCP/IP to Modbus Serial Gateway assigned a IP Address of 192.168.3.101 would use the Modbus Protocol Unit ID = 1 to point to the Modbus Serial Device with Modbus Address 01 connected to the serial port.
 
The Air2O main control board has a LCD screen and keys to navigate the menu system. This would seem like the expected location to set the Modbus slave ID. Is there a parameter on the LCD screen for the Modbus slave ID?
dear,
there is no option on LCD screen to change the salve ID
 
If you cannot change the Modbus Address your only solution would be to use a Modbus TCP/IP to Modbus Gateway for each device. There are also Modbus TCP/IP to Modbus Gateways with multiple serial ports. Typically in a Gateway you can configure routing in the device to point to a specific device as an example a Modbus TCP/IP to Modbus Serial Gateway assigned a IP Address of 192.168.3.101 would use the Modbus Protocol Unit ID = 1 to point to the Modbus Serial Device with Modbus Address 01 connected to the serial port.
Dear,
am planning to put modbus rtu to bacnet gateway for each device. but it will increase the coast of my project. that's why am looking for some other possibilities to change slave ID's
 
Top