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33 PROGRAMMING
33.2 Cautions for Program Creation
Positioning instruction activation timing
■When the absolute position detection system is used
For the axis in which the absolute position detection system is used, activate the DABS instruction when the servo amplifier is
powered on. (Page 506 Absolute Position Detection System) After the ABS data has been read, the servo-ON (SON is
on) status is retained, and it is disengaged when the DABS instruction is turned off. Activate the other instructions after the
DABS instruction has read the ABS data.
■When the pulse output monitor is on
If the pulse output monitor is on, a positioning instruction (excluding the DABS instruction) that uses the same axis cannot be
executed. (Page 415 Pulse output monitor)
While a pulse output monitor is on even after the positioning instruction drive contact is set to off, a positioning instruction for
the same output axis cannot be executed. Before re-executing a pulse output or positioning instruction, wait until the pulse
output monitor turns off and one or more operation cycles pass.
■When a user interrupt is used
Driving a positioning instruction requires multiple scans and has both rising processing and falling processing. Thus,
positioning does not operate normally if the positioning instruction is skipped by CJ instruction or if it is not executed every
scan like inside an interrupt program. However, pulse output continues. Eliminating the instruction by online change also
prevents the positioning from operating normally, and pulse output is stopped.
If the instruction is skipped, the complete flag does not turn on after the positioning operation stops. The complete flag turns
on if the positioning instruction is executed again when CJ instruction is canceled or the user interrupt program is executed
again. When the instruction is skipped, if disable all outputs (SM8034), pulse stop command, pulse decelerate and stop
command, or limit in the movement direction is detected during a scan in which the positioning instruction is not executed, the
positioning operation stops. The user-specified complete flag turns on, but the FX3 compatible complete flag (SM8029) does
not turn on.
Functions that share inputs and outputs
The inputs and outputs specified with the positioning parameter cannot be simultaneously used with another high-speed input/
output function depending on the combination. (Page 233 HIGH-SPEED INPUT/OUTPUT FUNCTION)
■CPU module
• Input
The following functions occupy inputs of the high-speed input/output function.
*1 If used simultaneously with another function, the input logic of the other function is applied.
*2 When external preset input and external enable input are used, the number of usable channels is decreased depending on the counter
type.
Function Up to CH/axis Device Simultaneous useable
function
FX5S/FX5U/
FX5UC
FX5UJ
Input interrupt
*1
Interrupt (Rising) 8 CH X0 to X17 The functions other than
high-speed counter (input A
phase, input B phase)
Interrupt (Falling)
Interrupt (Rising + Falling)
Interrupt (Rising) + Pulse Catch Cannot be combined
High-speed counter A phase input 8 CH
*2
X0 to X17
B phase input
External preset input Input interrupt
External enable input
Pulse width measurement 4 CH X0 to X7 Input interrupt
Positioning Near-point dog signal 4 axes 3 axes X0 to X17 • Input interrupt
• Zero signal
Zero signal 4 axes 3 axes X0 to X17 • Input interrupt
• Near-point dog signal
Interrupt input signal 1 4 axes 3 axes X0 to X17 Input interrupt
External start signal 4 axes 3 axes X0 to X17 Input interrupt
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