Q: 8. Are there also ATEX products available?

Thanks to specially approved components , AS-i can be used in ATEX applications up to 3D/3G.

Q: 10. What are the technical key data of AS-Interface?

Topology flexible structure Medium unshielded two-wire line for data and energy Cable length 100 m, expandable to up to 1,000 m, up to 3,000 m through fibre optics Number of I/Os 496 inputs + 496 outputs for digital, analogue and safe data Cycle time 5- 10 ms

Question 1

1. What is AS-Interface?

Accepted Answer

The actuator-sensor interface (As-i, ASI) is a manufacturer-independent standard for connection of actuators and sensors of the first field level. AS-Interface has become established as an economic smart wiring system in industrial automation.

A two-wire flat cable transmits data and energy. This considerably reduces wiring complexity as conventional wiring of each individual sensor or actuator to the controller is no longer required, saving the user considerable numbers of terminals, splitter boxes, input/output cards and cable lines.

The AS-i masters control the data exchange to the sensor/actuator level and communicate rapidly with the superior control level. They can be used as independent, decentralised controllers or as gateways to all common fieldbus systems. The range includes interfaces with EtherNet/IP, PROFIBUS, Profinet, EtherCAT or CANopen.

The decentralised AS-Interface I/O modules connect binary and analogue sensors and actuators to the gateway or PLC via AS-Interface.

Question 2

2. Is AS-Interface manufacturer-neutral?

Accepted Answer

Yes. AS-i is standardised via the AS-INTERNATIONAL ASSOCIATION e.V., of which ifm is also a member.

Question 3

3. Why do I need a special flat cable?

Accepted Answer

Thanks to the flat cable, the AS-i participants can be installed with reverse polarity protection. In addition, power transmission and communication take place via the same cable.

Question 4

4. Why do I need an AS-i power supply?

Accepted Answer

AS-Interface requires a voltage range of 26.5 to 31.6V for operation and communication. Through this power supply the AS-i slaves provide the required voltage to the connected periphery.

ifm AS-i power supplies used at NOBA

Question 5

5. How many masters can I have in the system?

Accepted Answer

AS-Interface is a single-master system. However, ifm controllers have up to two separate AS-i masters for two independent AS-i networks in one housing.

Question 6

6. Are there connections to higher-level fieldbuses?

Accepted Answer

All AS-i masters from ifm connect to superior fieldbuses with nearly all common industrially used protocols, such as EtherCAT, EtherNet/IP, PROFINET, Profibus or Modbus TCP.

Question 7

7. Can I also transmit safe signals via AS-i?

Accepted Answer

Yes. The extension of AS-i Safety at Work products is easily done, even on the same yellow cable. You will need safe AS-i slaves and an AS-i safety monitor or AS-i safety controller.

Question 8

8. Are there also ATEX products available?

Accepted Answer

Thanks to specially approved components, AS-i can be used in ATEX applications up to 3D/3G.

Question 9

9. What is the savings potential of AS-i?

Accepted Answer

Smaller PLC modules
Smaller control cabinets
Less cabling
Standardised connection lines
Less on-site splitter boxes
Facilitates documentation
Shorter commissioning times

Question 10

10. What are the technical key data of AS-Interface?

Accepted Answer

Topology	flexible structure
Medium	unshielded two-wire line for data and energy
Cable length	100 m, expandable to up to 1,000 m, up to 3,000 m through fibre optics
Number of I/Os	496 inputs + 496 outputs for digital, analogue and safe data
Cycle time	5- 10 ms

Question 11

11. What is the cycle time and slave order for AS-i communication?

Accepted Answer

Slave order and cylce times

Scanning order: (single slaves + A slaves + B slaves without associated A slaves) ► (single slaves + B slaves + A slaves without associated B slaves)

Example, scanning order based on an example configuration with the AS-i slave addresses:
1, 2A, 3A, 6A, 6B, 7, 15B, 22A, 22B
Cycle 1: 1, 2A, 3A, 6A, 7, 15B, 22A
Cycle 2: 1, 2A, 3A, 6B, 7, 15B, 22B
Cycle 3: 1, 2A, 3A, 6A, 7, 15B, 22A

Every AS-i communicaiton (master call / slave response) requires cycle time of 156 µs
After the AS-i master has exchanged data with every AS-i slave, an "inclusion call" is made. The AS-i master makes this call to check whether any new AS-i slaves have been connected to the system or whether previously failed slaves (configuration error) can be reached again. The duration of the inclusion call is also 156 µs.
- In the case of 31 AS-i slaves with single addresses (1...31), this results in a maximum cycle time of:
  t_max= (31+1)*156 µs = 4.992 ms ~ 5 ms
- In the case of 62 AS-i slaves with extended address mode, this results in a maximum cycle time of:
  t_max= (62+2)*156 µs = 9.984 ms ~ 10 ms

Question 12

12. What are the different operating modes of the AS-i masters?

Accepted Answer

AS-i master operating modes

Projection mode: The AS-i master communicates directly with all detected AS-i slaves. The saved AS-i configuration is not monitored.

Protected mode: The AS-i master only communicates with the AS-i slaves that are stored in its configuration. A new configuration can be saved at any time. The stored- configuration is monitored, generating an error message when there is a missing or new slave. Automatic addressing of AS-i slaves is only possible in this operating mode.

Question 13

13. What are the different slave lists?

Accepted Answer

The AS-i master uses slave lists to keep record of the connected AS-i slaves.

LPS = List of Projected Slaves
Containing all AS-i slaves that belong to the saved configuration (projection).

LDS = List of Detected Slaves
Containing all currently detected AS-i slaves of the AS-i network

LAS = List of Activated Slaves
Containing all AS-i slaves with which the AS-i master is currently in a cyclic data exchange

The above slave lists always contain the AS-i slave addresses and the complete AS-i profile. They are also available in binary form (1 bit per possible AS-i slave), allowing a simple programmatic evaluation in the PLC.

Other slave lists in binary form:
LCE = List of slaves with configuration errors
LCEMS = List of missing slaves
LCEAS = List of additional slaves
LPF = List of slaves with periphery fault
LDAE = List of addresses where double/multiple addressing has been detected

FAQ about AS-Interface

Efficient ifm AS-i power supplies used at NOBA Verbandmittel