Creating Ladder Logic Programs 4–13
About the Logix5550 Ladder Logic Program
Rung Description
0001 When the machine Start push button is pressed, the Logix5550 sends a START 
command to the drive. The drive will start if no STOP command is being sent 
by the Logix5550 or any other control device. (Start button is a normally open 
contact in this example.) SCANport products will start only if the start bit 
transitions high while the stop bit is already low.
In the example, we use rack 02 and starting group module word 0. The tags are 
configured to represent this address.
0002 When the machine Stop push button is pressed, the Logix5550 sends a STOP 
command to the drive. (Stop button is normally closed contact in this example)
0003 A frequency command is transferred from the Logix5550 data table to the drive. 
A range of 0 to 32767 is equivalent to zero to maximum frequency. (In this 
example, the drive frequency select parameters are set to receive a frequency 
reference from the Remote I/O module.)
0004 When the machine Jog button is pressed, the Logix5550 will send a JOG 
command to the drive. The drive will start and run at the programmed jog 
frequency if no STOP command is being sent by the Logix5550 or other control 
device. (Jog button is normally open contact in this example.)
0005 When the machine Clear Faults push button is pressed, the Logix5550 sends a 
CLEAR FAULTS command to the drive. (Clear Faults button is a momentary 
normally open contact in this example.)
0006 When the drive is running, the Logix5550 will receive a Drive Running status 
bit.
0007 When the drive is faulted, the Logix5550 will receive a Drive Faulted status bit.
0008 A value is moved from the Logix5550 data table into the drive parameter 
specified by the Data In A1 parameter in the drive.
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