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Si2035 Hardware Manual
920-0108B
1/26/2018
Connecting Limit Switches
The CWLIMIT and CCWLIMIT inputs are used for connecting end of travel sensors. These inputs are differential,
which allows you to use signals that are sinking (NPN), sourcing (PNP) or differential (line driver). By connecting
switches or sensors that are triggered by the motion of the motor or load, you can force the motor to operate within
certain limits. This is useful if a program or operator error could cause damage to your system by traveling too far.
The limit inputs are optically isolated. This allows you to choose a voltage for your limit circuits of 12 to 24 volts
DC. This also allows you to have long wires on limit sensors that may be far from the drive with less risk of intro-
ducing noise to the drive electronics. The schematic diagram of the limit switch input circuit is shown below.
Si2035 Limit Input diagram
Wiring a Mechanical Limit Switch
You can use normally open or normally closed limit switches. Either
way, wire them as shown here.
Wiring a Limit Sensor
Some systems use active limit sensors that produce a voltage output rather than a switch or relay closure. These
devices must be wired differently than switches.
If your sensor has an open collector output or a sinking output,
wire it like the example left:
If the sensor output goes low at the limit, select the option “closed” (in the software). If the output is open, or
high voltage, choose “open”.
Other sensors have sourcing outputs. That means that current can flow out of the sensor output, but not into it.
In that case, wire the sensor this way: