Allen-Bradley devicenet modules in logix5000 control systems Manual Do Utilizador

Publication DNET-UM004A-EN-P - March 2004

Before You Begin        1-9

The default baud rate for a DeviceNet network is 125K bits/s. This is 
the easiest baud rate to use and is usually sufficient.

The 2 most common methods to set the baud rate of a device are:

autobaud feature

At power up, the device automatically sets its baud rate to the baud rate of the first device it hears on the network. It 
remains set until the device powers up again.

The network requires at least one device with a fixed baud rate so the autobaud devices have something against 
which to set. Typically, scanners and network interfaces have a fixed baud rate.

switches or 
pushbutton on the 
device

Some devices have switches or a pushbutton that set the baud rate.

• The device reads the switch setting at power up.
• Typically, the switch lets you select either:

• autobaud
• fixed baud rate of 125K, 250K, or 500K

• If you change the switch setting, you have to cycle power to the device before the change to takes effect.

There are exceptions. For example, the 1756-DNB module has a pushbutton, which only lets you set the baud rate if 
the module is unconnected from the network or network power is off. Once you change the baud rate, the module 
automatically resets to the new baud rate.

software

Some devices require a programming device to set its address. For example, you can use your computer and the 
DeviceNet Node Commissioning tool (software) to set the baud rate of a device. The Node Commissioning tool is 
available:

• automatically when you install RSNetWorx for DeviceNet software
• as a separate application on the RSLogix 5000 software CD, revision 13.0 or later