Comtrol Modbus TCP User Guide - Manual (Page 88)

88 - Appendix A. Programming the PLC via Concept DeviceMaster UP Modbus/TCP User Guide: 2000447 Rev. I
Read Serial Data via Read Holding Registers Message
A.2.2.1. Read Serial Data via Read Holding Registers Message
The following screen depicts a Read Holding Registers message used to receive raw serial data in ladder logic.
Where:
SLAVEREG Refers to the port receive data address (+1 for use with Concept).
NO_REG
The maximum receive message size in 16 bit words. The maximum size of 100 includes
two words for the sequence number and length and then up to 196 bytes of serial data.
NDR The done flag.
ERROR The error flag.
REG_READ The destination address to place the received data.
STATUS The message status word.
AddrFld This contains the PLC Modbus/TCP slot/index and IP address of the DeviceMaster UP.