holding register modbus address

hello friends

I'm using Tia portal 2014 and s7-1200 PLC

im going to connect the pc to s7-1200 via modbus tcp.

my simple question is this:

what is modbus address of a variable in db?

if i had only one db it was 40001

but for the second db how can i know the address?

Hi

what is modbus address of a variable in db?

You can get modbus register address from modbus device's manual or  from modbus equipment manufacture. Which is modbus device?

if i had only one db it was 40001.but for the second db how can i know the address?

???.40001 may be modbus holding register address.

Please elaborate what you need.You need to send REQ for modbus register address via modbus tcp block for any modbus vaues that can be moved to any DB.

Modbus registers:

The types of registers referenced in Modbus devices include the following:
• Coil (Discrete Output)
• Discrete Input (or Status Input)
• Input Register
• Holding Register

Whether a particular device includes all of these register types is up to the manufacturer. It is very common to find all I/O mapped to holding registers only. Coils are 1-bit registers, are used to control discrete outputs, and may be read or written. Discrete Inputs are 1-bit registers used as inputs, and may only be read. Input registers are 16-bit registers used for input, and may only be read. Holding registers are the most universal 16-bit register, may be read or written, and may be used for a variety of things including inputs, outputs, configuration data, or any requirement for "holding" data.

Most Control Solutions I/O devices use holding registers for all types of inputs and outputs. In most cases, the same I/O is accessible as other register types as well, with the I/O status or value being mirrored in multiple registers.

hidian

hello friends

I'm using Tia portal 2014 and s7-1200 PLC

im going to connect the pc to s7-1200 via modbus tcp.

my simple question is this:

what is modbus address of a variable in db?

if i had only one db it was 40001

but for the second db how can i know the address?

A sample for  Modbus register address manual of  Siemens  Power Meter SICAM P enclosed  in this link. Similarly get the modbus register address manual of the device that you use from its manufacture.

The modbus address of the first holding register in a DataBlock1 is 400001

what is the address of the first holding register of Datablock2 ?

very simple question that i can not explore from documents

hidian

The modbus address of the first holding register in a DataBlock1 is 400001

what is the address of the first holding register of Datablock2 ?

very simple question that i can not explore from documents

What do you mean by DataBlock1&2?

You need only one datablock for modbus buffer values.

This datablock name will be mentioned in the modbus TCP block- PTR section.

Also mention Register address eg: 40001 and Length : 10.

Its means REQuesting modbus values of resister 40001 to 40010.This values come on the PTR data block.

If you have PTR datablock with an array of words with address DB1.DBW00-DB1.DBW09

DB1.DBW00-MODBUS VALUE OF REGISTER ADDRESS 40001

DB1.DBW01-MODBUS VALUE OF REGISTER ADDRESS 40002

DB1.DBW02-MODBUS VALUE OF REGISTER ADDRESS 40003

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DB1.DBW09-MODBUS VALUE OF REGISTER ADDRESS 400010