Specifications

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3401 Manual
Point I/O Stepper Module
Revision 2.0
Chapter 5: Command Mode Output Data
(Eight 16 bit words sent from the PLC to the 3401 module)
All stepper motor operations are performed in command mode. This mode is entered, after a successful
configuration file has been transferred to the stepper controller, by resetting the Mode Flag bit 15 of
Output Word 0. In Command Mode, the PLC program can issue commands and activate different
operations or moves. A move profile typically consists of a Target Position, Programmed Speed,
Acceleration, and Deceleration parameters. The following table shows the function of the output words.
16 bit Output
Word
Function Units Range
0 Command MSW See description below
1 Command LSW See description below
2 Target Position MSW
Steps
-8,388,608 to 8,388,607
3 Target Position LSW
4 Programmed Speed MSW
Steps/Second
Starting Speed to
1,000,000
5 Programmed Speed LSW
6 Acceleration Steps/ms/sec 1 to 2000
7 Deceleration Steps/ms/sec 1 to 2000
Command Mode Programming Notes
1. Only a single bit can be set at any one time in the Most Significant Command Word.
2. A Command Error will be generated if a move operation is started before the previous move
operation is completed. A move operation should only be started if the Move Complete, Stopped,
or Hold status bits are set.
3. The Target Position and Programmed Speed parameters are divided into two words, MSW and
LSW. The upper word (MSW) has the 1000s places and the lower word (LSW) has the 1s, 10s
and 100s places
4. A negative Target Position value will be programmed as a negative decimal number in both the
MSW and LSW data words. For example;
5. The Position parameter has a range of -8,388,608 < Target Position < 8,388,607.
6. The LSW of the Target Position has a range of –999 to +999.
7. The Programmed Speed has a range of Starting Speed < Programmed Speed < 1,000,000
steps/sec.
8. The LSW of the Programmed Speed has a range of 0 to 999.
9. The acceleration and deceleration parameters have a range of 1 < acceleration/deceleration <
2,000 and is measured in steps/msec/sec. Multiply the acceleration rate by 1000 to convert it
from steps/ms/sec to steps/sec/sec.
10. Switching the PLC to Program Mode will cause any move operation to stop and the position to
become invalid.
Value MSW LSW
-12,345 -12 -345
12,000 12 0
-12,000 -12 0
345 0 345
-345 0 -345