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Video: How do I read data from a Modbus TCP device using the embedded Ethernet port on a Unity Premium PLC?

Published date: 09 November 2018

Programming Modicon Premium PAC to Read Device Data via Ethernet Port

Product Line:
Premium, Unity Pro

Unity Pro software


To read data from a Modbus TCP device using the Premium PLC with embedded Ethernet port , follow the steps below:
1. Create a Premium project with an embedded Ethernet port on the CPU
2. Create an Ethernet network under "communication" within the project browser
3. Double click on the newly created network and under the "IP configuration" tab, enter the desired IP address and subnet mask
4. Select the "messaging" tab and check the "XWAY profile" option.
5. Enter an XWAY address and IP address under the connection configuration section. The XWAY address comprises of a network and station number. The network number can be between 0 and 127 and the station number must be          between 100 to 163 for Modbus TCP messaging. Example of XWAY address is 1.101
6. Create a section and add the READ_VAR function block
In the example below, the Premium PLC is reading 5 words starting a 40400 in the remote device

READ_VAR (ADR := ADDR('{1.101}SYS'),
          OBJ := '%MW'                          (* Type of objects to read for Premium PLC: '%MW': internal words *)
          NUM := 400                             (* Index of the first object to read. *)
          NB := 5                                     (* Number of objects to read. *)
          GEST := %MW50:4                 (* Exchange management table *) 
          RECP => receive_buffer);          (* Word table containing the value of the objects read. The length of this array must be greater than or equal to NB*) 

%MW52 := 20;  (* The third word of the management table is managed by the user which defines the maximum response time using a time base of 100 ms.*)

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