Safety: controller uses Ethernet; inductive sensor positions robots

By Control Engineering Staff March 23, 2006
Sick IN4000 Inductive Safety Sensor is rated Category 4, in accordance with EN 954-1 (a European standard), and has an IP67 enclosure rating. Input and output signals on the sensor correspond to EN 61 131-2 and are compatible with the I/O signals on a safe PLC.

Rockwell Automation added EtherNet/IP networking connectivity to its Allen-Bradley GuardPLC line of safety controllers, helping OEMs and end-users cost-effectively share critical safety-related information between safety and standard control systems. In a separate safety development, Sick , a manufacturer of sensors, safety systems, and automatic identification products for industrial applications, offers the IN4000 Inductive Safety Sensor, activated by metal, so it does not require a separate coded actuator. It can be connected to an IN4000 relay evaluation unit, selective Sick safety bus networks, or approved third-party safety controllers.
Four distributed I/O (DIO) modules also were recently added to the Allen-Bradley GuardPLC line of safety controllers: 8/8 digital input/output (I/O), a 16/8 digital I/O, an analog I/O, and relay output. Two digital I/O modules have bipolar outputs for use with robot controllers and other specialty output devices. Analog module has eight safety-rated inputs and four standard analog outputs. Relay module has eight isolated relays for switching power or providing a dry contact as an enable signal. GuardPLC 1600 and 1800 controllers feature a built-in, four-port Ethernet switch, making it simple to connect the I/O blocks, the company says.
Sick’s IN4000 Inductive Safety Sensor is said to be ideal for robot axis and gantry positioning to find home or safe, end-of-travel positions and to limit robot motion outside of its restricted space. It can also be used as a safeguard, for monitoring door position on a machine; the sensor can trigger a robot to stop if a door opens. The sensor is tamper-resistant and has built-in dual components and self-checking to ensure operation as a safe positioning device. It also resists shock and vibration. LEDs indicate status; self-monitoring detects failures, such as a coil break, short circuit, or cable break.

edited by Mark T. Hoske, Control Engineering editor in chief,