Digi 90000566_H manual Modbus options

set ia

[modbus options]

The configuration options specific to the Modbus protocol, which include:

errorresponse={onoff}

Controls behavior for common run-time errors such as no response from the slave device. By default, “errorresponse=off” for serial Modbus protocols, since most masters assume no response when errors occur. Having this option off also actively filters out returning Modbus exception codes 0x0A and 0x0B from remote Modbus/TCP slaves.

broadcast={onoffreplace}

Specifies how to handle incoming requests with a slave address set to the broadcast value. For Modbus, this is 0. The default is to replace 0 with 1, which was selected to overcome the fact that many Modbus/ TCP clients always send requests to unit ID zero (0) and do not want this treated as a broadcast.

on

Tells the Digi device to send requests as broadcast to the destination device(s) and not expect any response message.

off

Tells the Digi device to throw away the broadcast request.

replace

Changes a broadcast request to a normal request by replacing the unit ID 0 with a value of 1.

fixedaddress={auto1-255}

Used to override the Modbus protocol address (unit ID) with a fixed address.

auto

When set to “auto,” the protocol address will not be overwritten.

1-255

Setting it to a fixed number from 1-255 forces this value to be used for all Modbus requests.

The default setting is “auto.”

124 Chapter 2 Command Descriptions