3–13
Chapter 3 – Installation and Wiring
GLC2400/2500/2600 Series User Manual
After the GLC runs the program, the timing of the ON/OFF sig-
nals to an output device is carried out simultaneously.
For example, an electromagnetic switch for forward and re-
verse motor rotation could be turned ON and OFF at the same
time. Therefore, when the main contacts for the power cir-
cuits of both the forward and the reverse motor rotation are
turned ON and OFF at the same time, an R Phase and a
T Phase short circuit may occur. Use the above interlock, or a
mechanical interlock equipped with an electromagnetic switch,
when designing a forward/reverse rotation circuit.
Interlock Circuit 2
If there is a possibility that a GLC failure could cause an accident, use an external
hardware device to include a failsafe element in the design of the interlock circuit.
For example, if the system first needs to stop the Travel Motor whenever the Unit
Travel Limit Switch is activated, include the Unit Travel Limit Switch in the GLC
input. The following circuit uses a hardware method to ensure that the Travel
Motor is stopped.
This applies to hardware. Do NOT rely on software to process the interlock design.
Interlock Circuit 1
Create an interlock circuit outside the GLC (below), to control a motor’s forward/
reverse rotation circuit using a GLC or PLC connection.
Electromagnetic
switch for motor
rotation
GLC
Auxiliary B contact of electromagnetic
switch for motor reverse rotation
Motor rotation signal
(forward)
Electromagnetic switch for
motor reverse rotation
Auxiliary B contact of electromag-
netic switch for motor rotation
Motor reverse
rotation signal
GLC
U n i t
T r a v e l
L i m i t
S w i t c h
Emergency
S t o p
S w i t c h
Directly input to Emergency
Stop Circuit in Control unit
U n i t T r a v e l
L i m i t S w i t c h
T r a v e l M o t o r C o n t r o l S i g -
n a l
T r a v e l M o t o r
C o n t r o l C i r -
c u i t