60 Rockwell Automation Publication 1766-UM001O-EN-P - September 2021
Chapter 4          Communication Connections
5. Use the Up arrow to change the indicator position so that it points to 
Enable. Press OK to change to the default communication mode. 
The DCOMM Mode Change Notification screen display. It indicates that 
the communication configuration is changed to the default 
communication mode. The DCOMM status indicator displays a solid 
rectangle.
 
If you change to the user-defined configuration from the default 
configuration mode by selecting Disable and pressing OK, the DCOMM 
Mode Change Notification displays.
6. Press ESC to return to the Advanced Set Menu screen, as shown in step 3
.
Connect to the RS-232 Port There are two ways to connect the MicroLogix 1400 programmable controller 
to your personal computer using the DF1 protocol: using a point-to-point 
connection, or using a modem. Descriptions of these methods follow.
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ATTENTION: All devices connected to the RS-232/RS-485 communication port 
must be referenced to controller ground, or be floating (not referenced to a 
potential other than ground). Failure to follow this procedure may result in 
property damage or personal injury.
• For 1766-L32BWA controllers, the COM of the sensor supply is also connected to 
chassis ground internally. The 24V DC sensor power source should not be used to 
power output circuits. It should only be used to power input devices.
• For 1766-L32BXB controllers, the VDC NEUT or common terminal of the power 
supply is also connected to chassis ground internally.