AS-Interface I/O modules - System description

The AS-i modules for use in control cabinets are compact in size and offer up to 4 inputs and 4 outputs allowing expansion to take place but keeping unused I/O down to a minimum. Communication to the PLC is handled in the usual way via an AS-i master.

SmartLine modules for universal use in control cabinets
Due to their slim-line design and the latest AS-i technology the SmartLine modules are suitable for universal use. Thanks to AS-i 2.1 specification up to 62 digital modules or 31 analogue modules can be connected to the AS-i master.
Further characteristics are:
  • Robust DIN rail mounting
  • Addressing socket on the front
  • Combicon terminals for quick replacement
  • Screw terminals, insulation displacement terminals or cage clamps
  • AS-i QIC for uninterrupted bus wiring
  • All status LEDs clearly visible on the front
  • Peripheral fault indication
Analogue modules for the control cabinet - Introduction
In addition to binary signals analogue control signals must often be processed in industrial process automation, e.g. temperature or pressure values. In the fields of conveyor technology, machinery and plants are speed-controlled via the transmission of continuous signals. In principle it does not matter whether the analogue values represent temperature, speed, pressure or another continuous quantity required for the process. In general the analogue value is converted into a voltage or current value by a suitable sensor and is thus available for the process. By means of the analogue I/O modules these values can then be digitally transmitted to the controller via the standard AS-i cable.

ProcessLine · Introduction
AS-interface has become the established standard in traditional mechanical engineering. Some machine and plant builders of the bottling and brewery industries have surged ahead and opened the door for an application with completely new requirements. First the traditional distribution cabinets are equipped with AS-i control cabinet modules. The easy AS-i bus technology for the distribution of binary and analogue signals reduces the so far common high number of parallel cables. However, the expensive stainless steel switch boxes required on site undo part of the cost savings for wiring. This is where the idea of ifm ProcessLine comes in: modules completely made of stainless steel that can replace many switch boxes.

AS-i in the food industry
In existing AS-i applications in the food industry the modules for field applications or control cabinets are located in switch boxes to protect the units from humidity and cleaning agents. The boxes must be made from high-grade stainless steel since normal steel boxes would corrode within a short time. The ProcessLine modules are the first high-grade stainless steel AS-i modules for direct installation in the field. All process connections are M12 connections with radial sealing. This means: Never again install cable exits, remove external cable sheaths, strip individual cores and connect them to terminals. With prewired cables there are no wiring faults and loose connections any more. The AS-i flat cable connection technology can also be used due to corresponding stainless steel insulation displacement connectors. All components have protection rating IP 69 K.



Digital modules CompactLine · Introduction
By means of the digital I/O modules binary signals of standard sensors can be transmitted to the controller via the AS-i cable. The controller can, however, also transmit binary switched signals to the actuators on site via the outputs of the I/O modules. With the additions according to specification 2.1 the tried and tested compact modules have been modified and now find their place on the market of AS-i field modules as CompactLine modules. The A2Si chip from AMI is used. New functions are available. The extended addressing mode allows communication with up to 62 slaves. Peripheral faults are displayed and transmitted to the AS-i master (according to the specification V2.1, e.g. controller e). What is also new is the option of infrared addressing. When the modules were modified, tried and tested features such as full potting and compact housing remained. The slaves are connected to the AS-Interface via the classic flat cable and feature protection rating IP67. The LEDs on the front panel indicate the input/output states, the supply voltage and possible faults of the module.

Operating principle
When the master and the slaves communicate, the AS-i master transmits information to the AS-i network. This information comprises, among others, the slave address and the output information for the connected actuators of the called slave. The slave replies to the AS-i master with the input information of the connected sensors. If a slave provides inputs and outputs, bidirectional data exchange is used. For slaves which only have outputs the master transmits the output signals to the slave. The response of the called slave, however, does not contain input information but merely "empty" bits. If a slave is designed as an input slave, the information bits are not used when the slave is called - the called slave, however, replies with the input information of the connected sensors. In this way 4 inputs and 4 outputs can be realised with only four information bits per slave.



Digital modules ClassicLine · Introduction
By means of the digital I/O modules binary signals of standard sensors can be transmitted to the controller via the AS-i cable. The controller can, however, also transmit binary switched signals to the actuators on site via the outputs of the I/O modules. With the extension of AS-interface according to specification 2.1 the product range for field applications is considerably complemented by the ClassicLine family. The use of the A2Si chip enables a number of additional functions. Features such as "extended addressing mode” (i.e. communication with up to 62 slaves), "indication of peripheral faults and communication errors" (with the option of transmission to and evaluation by an AS-i master with the specification 2.1, e.g. controller e) are available. Furthermore, these modules have an infrared addressing interface allowing addressing even when connected. All operating and display elements are located on the front display. The LEDs indicate the signal states of the inputs and outputs, the operating voltage and possible faults. The ClassicLine modules enable exact fault location and their compact design and high protection rating make them perfectly suitable for installation in the field. The connection of the ClassicLine modules to the flat cable is done via the tried and tested conventional flat cable lower parts and enables fast and reverse polarity protected connection for the user. The variety of types of the ClassicLine family enables the user to find the optimum configuration for the required number of inputs/outputs.

Operating principle
When the master and the slaves communicate, the AS-i master transmits information to the AS-i network. This information comprises, among others, the slave address and the output information for the connected actuators of the called slave. The slave replies to the AS-i master with the input information of the connected sensors. If a slave provides inputs and outputs, bidirectional data exchange is used. For slaves which only have outputs the master transmits the output signals to the slave. The response of the called slave, however, does not contain input information but merely "empty" bits. If a slave is designed as an input slave, the information bits are not used when the slave is called - the called slave, however, replies with the input information of the connected sensors. In this way 4 inputs and 4 outputs can be realised with only four information bits per slave.



Analogue modules - Introduction
In addition to binary signals analogue control signals must often be processed in industrial process automation, e.g. temperature or pressure values. In the fields of conveyor technology, machinery and plants are speed-controlled via the transmission of continuous signals. In principle it does not matter whether the analogue values represent temperature, speed, pressure or another continuous quantity required for the process. In general the analogue value is converted into a voltage or current value by a suitable sensor and is thus available for the process. By means of the analogue I/O modules these values can then be digitally transmitted to the controller via the standard AS-i cable.

Operating principle
As for the basic characteristics of AS-i an information share of 4 bits was defined for each slave, the transmission of analogue values which generally consist of more than 4 bits takes a little more time. Practically, the analogue values are transmitted in data fragments in several AS-i cycles and "reassembled" to a complete analogue value by the driver module in the AS-i master. In the user program access to an analogue value is limited to reading it at a defined address. First, certain manufacturer-independent slave profiles were defined regulating the data exchange of the analogue slaves with the AS-i master. These are the profiles S-7.1 and S-7.2 (according to the AS-i specification V2.0) and the profiles S-7.3 and S-7.4 (according to the AS-i specification V2.1). If slaves with the profiles S-7.1 or S-7.2 are used, a function block must be processed in the software of the higher-level controller implementing data communication with the analogue slave. This procedure, however, becomes less important as these drivers are no longer necessary as analogue slaves with the profiles S-7.3 and S-7.4 are available. The AS-i masters available on the market can clearly recognise these slaves by their profile and then start data exchange themselves. The necessary effort is practically reduced to "plug & play". An additional software module is not necessary as it is integrated into the firmware of the AS-i master. The transmission of analogue data takes longer when using slaves with the profiles S-7.1 and S-7.2 than for slaves with the profiles S-7.3 or S-7.4 because data communication depends on the cycle time of the higher-level plc.



Digital module ClassicLine ATEX
The standard AS-i bus system so far exclusively used in non-hazardous areas can now also be used for zone 2 and zone 22 (non-conductive dusts). The AS-i ATEX modules can be installed directly in the corresponding environments. This eliminates the need for complex control cabinets with conventional wiring. The remaining AS-i system consisting of AS-i master, power supply, cable, etc. can be used unchanged. With the extension of AS-interface according to specification 2.1 the product range for field applications is considerably complemented by the ClassicLine family. The use of the A2SI chip enables a number of additional functions. "Indication of peripheral faults and communication errors" (which can be transferred to and analysed by an AS-i master of specification 2.1 such as controller e) are available. These modules also feature an infrared addressing interface to allow addressing after installation. The ClassicLine modules enable exact fault location and their compact design and high protection rating make them perfectly suitable for installation in the field. The connection of the ClassicLine modules to the flat cable is done via the tried and tested conventional flat cable lower parts and enables fast and reverse polarity protected connection for the user. The LEDs indicate the signal states of the inputs and outputs, the operating voltage and possible faults. The variety of types of the ClassicLine family enables the user to find the optimum configuration for the required number of inputs/outputs.

More information

System overview — AS-Interface I/O modulesSelector — AS-Interface I/O modulesProduct Innovations — AS-Interface I/O modules


The SmartLine modules are especially slim.


Analogue value detection of system pressure.


Process Line module front and rear view.


CompactLine M12 - the robust field modules.


ClassicLine modules for field applications.


Imperative: temperature detection in plants and machinery.


ClassicLine modules for field applications in hazardous areas.