How can find register address of slave device with modbus poll

I connect to DELCOS PRO V3 via RS485 Modbus RTU. I don't know address of register to read or write. I read holding register with try , but i can't write on device. Could you please help me to find address of register to command on compressor?
 
The device vendor supplies the information as to what data resides in which Modbus register (usually described as a 'map'), and usually describes what the format the data is.

There is absolutely NO general, industry-wide assignment of data to Modbus registers, the assignment of data to registers it is always the decision and implementation of the device vendor.

The device vendor has to supply that Modbus register information.

Sometimes when that is public, a forum participant will provide a link to the public documentation.

The loose affiliation of the this site with Modbus.org does not mean that this forum has access to device vendor data, whether public or proprietary.

The Modbus Function code for writing data to a holding register (that is writeable, as determined by the vendor) is 06 or 16 (decimal), as opposed to the Modbus Function code 03 for reading one or more Holding Registers.
 
The device vendor supplies the information as to what data resides in which Modbus register (usually described as a 'map'), and usually describes what the format the data is.

There is absolutely NO general, industry-wide assignment of data to Modbus registers, the assignment of data to registers it is always the decision and implementation of the device vendor.

The device vendor has to supply that Modbus register information.

Sometimes when that is public, a forum participant will provide a link to the public documentation.

The loose affiliation of the this site with Modbus.org does not mean that this forum has access to device vendor data, whether public or proprietary.

The Modbus Function code for writing data to a holding register (that is writeable, as determined by the vendor) is 06 or 16 (decimal), as opposed to the Modbus Function code 03 for reading one or more Holding Registers.
Hi
Thank for your attention, I can't find any document, but i find document for similar device (DELCOS pro 3100) .
I try to read and write with address that i see in this manual but it is not work. I try and find address of holding register, but i can't find address for command on
 
Hello Mahmoudian,

I had same problem. You should choose higher quantity on Modbus Poll (max: 125)
The picture that below would help you yo choose coil/register numbers gap. Probably you want to read input registers. It takes time but if you find a value, other values would be in same row. After you found out something except "0" you should change data type on Modbus Poll till it becomes understandable. That is a way I do. I hope it helps.
servlet.jpg
 
Top