TSX SAY 100
4.1
Review of the AS-i bus
At a Glance
Aim of this
Section
What's in this
Section?
This Section introduces the main characteristics of the AS-i bus.
This section contains the following topics:
Topic
Review of the AS-i bus
Overview of AS-i products from the Schneider catalog
Introduction to the main constituent elements
Example of AS-i bus topology
Main characteristics of the AS-i bus
Page
77
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Review of the AS-i bus
General
The AS-i bus is a field bus (level 0) and can be used to connect sensors/actuators.
This allows "Discrete" type information to be routed between a bus master and sensor/actuator slaves.
AS-i is made up of three major basic elements: l l l
A dedicated power supply providing 30 VDC voltage.
A bus master.
Slaves (sensors and actuators).
The main types of sensors/ actuators
1. Communication sensors/actuators:
With a built-in AS-i function they link up directly to the AS-i bus via a passive distributor or a T-piece connection.
2. The traditional IP65 sensors/actuators:
They connect to the bus via an AS-i interface (active distributor or Telefast IP20 discrete input-output bus interface). These interfaces connect the sensors and traditional actuators to the AS-i bus and provide them with dialog capacity on the bus.
Illustration:
Active distributor
Passive distributor
Connection T
AS-i Bus
AS-i function integrated
AS-i function integrated
AS-i function via interface
Traditional product
124 products maximum
(124 input information and 124 output information)
Communicating product Communicating product
31 products (sensors or actuators)
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Overview of AS-i products from the Schneider catalog
General
Actuators
AS-i
Non-exhaustive list of AS-i products from the Schneider catalog:
Man/machine dialog
Sensors
AS-i
Column lit
Start-up motor
Detector photoelectric
Inductive proximity detector
Button box
Keyboard
12 keys
Master Supply
Distributor active
2E/2S
4S
4E
For connection by M12 ports of sensors/actuators/units of dialog and signaling standards:
• inductive sensors.
• capacity switches.
• photoelectric barriers.
• end of run.
•
LEDs
• relays.
• solenoid valve.
Distributor passive
Bus interface
Telefast
4 channels for AS-i sensors/actuators connection equipped with
M12 sockets.
AS-i bus interface/discrete input-output.
•
4 I
•
4 O
•
8 I/O (4I + 4O)
For connection by screw or pull-out terminals of dialog sensors/ actuators/units of dialog and signaling standards:
•
2 or 3 wire inductive sensors.
• capacity switches.
• end of run.
•
LEDs
• relays.
• contactors.
• solenoid valve.
• resistance.
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Introduction to the main constituent elements
Cable
This transmits data and carries the power. It can be made up from: l l either an unshielded, polarized twin-wire AS-i ribbon cable.
Or a standard round, shielded or unshielded twin-wire cable.
Illustration:
TSX SAY 100
Active distributors
Guiding ribbon cable
Round cable
IP67 sealed interfaces for connecting sensors/actuators using M12 connectors.
These distributors are used to connect "traditional", non-communicating sensors/ actuators.
Illustration:
Active distributor for ribbon cable
Active distributor for round cable
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Passive distributors
IP67 sealed interfaces for connecting sensors/actuators using M12 connectors.
These distributors do not have any electronics and can therefore be used to connect the "communicating" sensors/actuators.
Illustration:
Passive distributor for ribbon cable
Passive distributor for round cable
SB2 Telefast discrete inputsoutputs/bus interface
IP20 sealed interface with built-in ASi- function. It enables connection to all types of
"traditional" non-communicating sensors/actuators via screw terminal blocks.
Illustration:
AS-i actuators
The direct motor starters and toggle switches in sealed boxes (IP54 and IP65) ensure electrical motors are controlled and protected up to 4KW at 400 VAC.
Illustration:
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AS-i sensors
TSX SAY 100 l Photo-electric detectors:
They ensure that all kinds of objects (opaque, reflective etc) are detected with 5 basic systems: barrier, reflex, polarized reflex, proximity and proximity with background blanked out. They offer an IP67 protection level.
Inductive proximity detectors: l
They detect all metal objects and provide information for the check functions on whether an object is present or not. They offer an IP67 protection level.
Illustration:
Man-machine interface products
l Button boxes:
These are made up of dialog tools, which are perfectly adapted to exchanging information between the operator and machine.
l
Keyboards:
Man/machine dialog tools, these have 12 touch sensitive keys. The information delivered is coded in BCD on 4 bits. They offer an IP65 protection level.
Illustration:
Signaling elements
l Illuminated columns:
Optical or sound signaling elements.
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Bus master
Built into a Premium/Altrium PLC station, the TSX SAY 100 module (AS-i bus master) manages all data exchanges on the AS-i bus.
Illustration:
AS-i power supply
Premium/Atrium station
AS-i dedicated power supply, designed to supply the components connected to the
AS-i bus.
The distribution of this power supply uses the same medium as that used for data exchange.
Illustration:
Connecting and branching accessories
T-piece connectors are used to make connections to the AS-i bus. These are designed for linking to AS-i ribbon cables or to ribbon/round cable branches.
Illustration:
T for ribbon cable
Branch ribbon/round cable
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Example of AS-i bus topology
General
Illustration:
Premium
AS-i master
AS-i Bus
Supply
AS-i
Sensors/actuators communicating
Interfaces with traditional sensors/ actuators
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Main characteristics of the AS-i bus
General
AS-i is a system in which exchange management is ensured by a single master who calls in succession, by scanning the bus, each detected slave and awaits a response.
The communication series frame carries: l
4 data bits (D0 to D3), which are the image of inputs or outputs according to the nature of the interface.
l 4 parametering bits (P0 to P3), which are used to set the operating modes of the interface.
P0 to P3 bits are used for "intelligent" devices, including AS-i ASIC (specific integrated circuit). Operation can be modified while it is running.
The address of the slave is coded on 5 bits.
At the request of the AS-i master, outputs are set and the inputs for AS-i devices are sent in the slave’s response.
Slave addressing
Each slave connected to the AS-i bus must have an address between 1 and 31
(coding on 5 bits).
The slaves delivered from the factory have the address 0 (the address of the slave is memorized in a non-volatile format).
Addresses are programmed using a terminal specifically for addressing, a XZMC11.
Note: When replacing a faulty slave whose address has been set, the address of the slave to be replaced can be updated automatically.
Identification of slaves
All slave devices connected to the AS-i bus are identified by: l l
An I/O Code (input/output distribution code).
An identification code, which completes the functional identification of the slave.
These identifications allow the AS-i master to recognize the configuration which is present on the bus
These different profiles have been developed by the AS-i Association. They are used to distinguish modules such as for inputs, outputs, mixed modules, "intelligent" device families, etc.
Maximum number of inputs/outputs
An AS-i bus can support a maximum of 31 slaves.
Each slave can have a maximum of 4 inputs and/or 4 outputs.
This makes it possible to manage a maximum of 124 inputs + 124 outputs, or 240 discrete inputs/outputs when all active devices have 4 inputs and outputs.
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AS-i cable
Topology and maximum length of AS-i bus
The topology of the AS-I bus is flexible. It can be perfectly adapted to meet the user’s needs (point to point, on line, tree structure etc.).
In every case, the total length of all the branches of the bus must not exceed 100 meters without a relay.
AS-i bus cycle time
The AS-i cable is a twin-wire link on which communications and power supply for the connected devises are transmitted.
The link does not need to be twisted.
The cross-section of wires can be from 2 x 0.75 mm
2
, 2 x 1.5 mm
2
or 2 x 2.5 mm
2
, according to the current consumed by the devices.
Reliability, flexibility
This is the cycle time between slave(s) and the TSX SAY 100 module.
The AS-i system always transmits information which is the same length to each slave on the bus. The AS-i cycle time depends on the number of slaves connected to the bus.
In the presence of 31 functioning slaves, this time period will be a maximum of 5 ms.
Reliable operation is ensured by the transmission process used (Manchester current and coding modulation). The master monitors the line supply voltage and the data sent. It detects transmission errors as well as slave failures, and sends the information to the PLC.
Exchanging or connecting a new slave during operation does not disturb communications between the master and the other slaves.
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