User's Manual

ManualsBrandsELPRO Technologies ManualsElectronicsUHF narrow band licensed radio band traceiver module

Elpro Technologies 450U-E Wireless Ethernet Modem & Device Server User Manual

Rev Version 1.0.12-Beta7 www.cooperbussmann.com/wirelessresources 45

Local Register

Enter the starting onboard I/O register number that the specified Modbus Master

transaction will transfer I/O to/from.

I/O Count

Specify the number of consecutive I/O register to be transferred for the specified

transaction.

Function Code

Specify the Modbus Function Code for the transaction.

Destination Register

Enter the starting I/O register number in the destination device that the specified

Modbus Master transaction will transfer I/O to/from.

Device ID

Enter the Modbus Device ID of the destination Modbus device

Server IP Address

Specify the IP Address of the destination Modbus TCP Server for the specified

transaction.

Sever Port

Server Port number used for Modbus TCP. Default/standard port number is 502

Response Timeout

Enter the timeout (in milliseconds) to wait for a response to the specified

transaction.

Comms Fail Register

Enter the onboard I/O Register number to store the communication status for the

specified transaction. If the register selection is a digital input register (10501), the

connection to the server. If a general Input register is used (30501-32500) for the

Comms Fail is it will write the status and the error code which is useful for

diagnosing communication problems. I.e. 0xFFxx where xx is the Modbus

Exception Code. See Appendix D - Modbus Error Codes for more details on the

Modbus Error Codes.

Note: When entering the Local or Destination registers you do not need to enter in the full Modbus

Address, i.e. 30001 or 10001 only the I/O address is needed as the Function Code determines what

type of command is being used.

E.g. if you wish to read from Destination register 30001 you need to select Function Code 04: Read

Inputs and then enter the Destination Register of 1.

Or if you wish to read register 10501 you need to select Function Code 02: Read Discretes and then

enter the Destination Register of 501.

Modbus TCP to RTU Conversion

The Modbus TCP to RTU Gateway allows an Ethernet Modbus/TCP

Client (Master) to communicate with a serial Modbus RTU Slave. The

450U-E makes this possible by internally performing the necessary

protocol conversion. The conversion is always performed by the

450U-E which is directly connected to the Modbus serial device (i.e.

only this module needs to have Modbus TCP to RTU Gateway

enabled).

The above example demonstrates how a Modbus/TCP Client (Master) can connect to one or more Modbus RTU (i.e.

serial) Slaves. In this example the 450U-E Access Point is configured with the connected serial port configured for

When enabled, the gateway converts the Modbus/TCP query into Modbus RTU and forwards

theme out the serial port to the Slave. When the serial device response the query arrives from the Slave, it is converted

back into a Modbus/TCP response and forwarded via the network to the Modbus/TCP Master. If no response was

received serially by the 450U-E within the configured Response Timeout, the 450U-E will initiate a number of retries

specified by the configured Maximum Request Retries.

The Modbus TCP to RTU Gateway may be configured to operate on either the RS-232 or RS-485 port.

Figure 51 - Modbus TCP-RTU