Adapter brings standard binary, or analogue factory sensors into the world of IO-Link
12 January 2010
The majority of sensor types available on the market today, with this new Simatic PX130C adapter, can connect with IO-Link systems without any special modification. IO-Link is the emerging communication standard for sensors and actuators in factory automation, and is an important advance because it provides a mechanism for the central diagnosis and detection of errors.
Simatic PX130C adapter for IO-Link systems
The adapter features a number of signal conditioning functions and extensive diagnostics functions. It is especially suitable for drive solutions such as speed control and monitoring as well as rotational direction recognition, and for fast counters.
The PX130C is installed as part of the supply cable, and requires no space in the control cabinet or complex terminal wiring.
The Simatic PX130C adapter with high IP67 protection rating functions as an adapter plug for the connection of up to two binary proximity switches or a single analogue sensor to the control level. For this purpose the adapter features two inputs which can be set to pnp or npn, one of which is digital, the other being either analogue or digital. The analogue input can be set to 0-20 mA, 4-20 mA or 0-10V. Most commonly-available sensor types can be connected to the adapter, which also applies to the more than 500 standard proximity switches of the Simatic PX portfolio from Siemens.
The Simatic PX130C adapter is equipped with a variety of functions. These include signal conditioning functions such as A/D conversion, rotational direction recognition, speed monitoring, input inversion, switching time measurement and timers with extended pulses, for example.
The diagnostic functions monitor connected sensors for wire breaks, short-circuits and overcurrent or undercurrent conditions. Configuration takes place in the standard engineering tool using the supplied IODD (IO-Link Device Description). Settings can be made for signal conditioning functions, for example. It is also possible to parameterise averaging values or switch-on muting and determine whether the positive edge or the falling edge of a connected sensor should be detected.
Sophisticated motion applications
The new adapter is especially advantageous when it is used in more sophisticated sensor applications. Typical areas of application include speed control and monitoring, standstill and slip monitoring or switchover and monitoring of start-up processes on drives. The wide range of functions means that the adapter can be used in all types of machines and plants, for example in wind power stations or CHP plants, belt conveyors and test stands or in large drives.
In addition a combination of simple proximity switches enables detection of rotational direction
in lift systems, stirrers, pumps or fans, or the slip monitoring of belt and hydraulic drives. The sensor adapter can detect both measure rapid counting processes up to five kilohertz as well as switching frequencies, thus also making it suitable for open and closed-loop control of agitators or oscillating conveyors.
The PX130C makes additional speed monitors and counter modules in the control cabinet superfluous, and there is also no need for extra rotary encoders for speed detection and rotational direction recognition.
Speed/standstill monitoring, frequency measurement
Speeds of up to 5,000 rpm can be measured and monitored on a shaft or cam with just one standard proximity switch. Minimum and maximum values, ramp-up time, and number of cams to be recorded can be freely configured via IO-Link. This permits cost-effective implementation of starting circuits on drives under load, controlled ramp-up of conveyor drives, monitoring of ramp-up times, or speed limiting.
Detection of direction of rotation
With the Y-adapter it is possible to connect two standard proximity switches which are arranged offset on a shaft or cam disk.
The offset in time between the two signals allows detection of the direction of rotation. Thus drives with large centrifugal masses but without braking or interconnected drives can also be safely started and reversed.
When using two sensors, SIMATIC PX130C determines and monitors the difference in speed (slip) from two rotary motions. This enables belt or chain drives to be monitored and also the monitoring of coiled or rolled materials – without the extra control unit which is usually required, and without having to provide a controller of higher performance.
The signal from a standard sensor can be counted by SIMATIC PX130C – up to a frequency of 5 kHz. The start value, counting direction and two limits can be freely selected via IO-Link. When a limit is reached, a switching signal is output via the process data. The counter is also reset via IO-Link – and all without expensive counter modules.
When two input channels are used, one can count upwards and the other downwards. It is also possible to use the switch status on the second channel to reverse the counting direction or to completely block the counter.
If voltage or current sensors are connected on the input side, SIMATIC PX130C transfers the measured values via IO-Link to the controller – without expensive, multichannel analog modules. The requirements for wiring and shield connections are also reduced, since an unshielded three-core cable is sufficient for the transmission. Scaling of the measured value is carried out by parameterising the limits directly in the IO-Link adapter. Scaling in the PLC program is thus not needed. The adjustable limits additionally allow fast monitoring of the measured signal.
Timer functions and inverting
Through the combination with a SIMATIC PX130C, signals can be switched on or off extended or delayed within wide ranges. Also possible to increase process safety: generation of a pulse of defined duration independent of the duration of the input signal. Furthermore, the input signal can be inverted by means of an IO-Link setting.
The input channels can be monitored by parameterisable limits for overcurrent or undercurrent. In this manner, typical faults such as open-circuit or short-circuit can be reliably detected and located, resulting in increased machine availability.
Further information can be found on the Internet at: www.siemens.com/io-link
Siemens Industry Automation
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