The Working Principle
AS-Interface Safety at Work is based on the standard AS-i log. Together with a connected AS-Interface safety monitor the system is designed for the transmission of safety-related informations. As base serves the transmission of dynamic code sequences which are stored
in each safe AS-Interface slave (8 * 4 bit code table). Through a “teach in” function the safety monitor reads in these code sequences when starting up the machine. During operation the safety monitor permanently compares the nominal and actual sequences of the safe slaves. If the safe slave (e.g. an E-stop) supplies a wrong code sequence, the safety monitor reacts immediately by switching off the machine.
When developing this concept it was attached great importance to an easy handling of the system. Same as on AS-Interface, each safety-related slave has to be assigned an address. The safety monitor identifies and registers these slaves automatically . This configuration must be acknowledged, printed and countersigned in order to ensure clear allocation of the safety-related signals to a cutoff-circuit.
Advantages of the AS-Interface”Safety at Work”
Schlegel E-Stop as Safe AS-Interface Slave
Functional Description
When connecting an emergency-stop pushbutton to an ASInterface network, the integrated code generator permanently produces 8 different 4-bit codes which are set up according to the S-7.B.Eprofile. Each E-stop has its own code sequence which is unique. When the E-stop button is pressed a case of emergency is signalised to the safety monitor by the code sequence “0000”. Should one of the two contacts of the E-stop fail, or should the E-stop actuator be separated from the contact unit, this fault is signalised to the safety monitor by a special sequence enabling precise diagnostics (defective hardware). The actual operating/diagnostic status of the E-stop can be indicated via the external connector (standard output DO), e.g. by an external 24V LED.
Slave Characteristics
*) refers only to the types ASI_SAW16A, ASI_SAW22A
Data Bits of the Outputs and Inputs
Outputs* | ||
data bit | info (Interface 3) | state |
D0 | 0 | off |
1 | on |
Inputs | ||
data bit | info (Interface 3) | state |
D0 ... D3 | acc. to profiles S-7.B.E*, S-0.B.e |
*) refers only to the types ASI_SAW16 and ASI_SAW22
Norms and Standards
Addressing of Slaves
The safe AS-Interface slaves are assigned a complete address. The easiest way to assign the addresses is to use a hand-held addressing device, which is directly connected to the slave via the Schlegel programming cable „ASI_PK500M12“. Individual addressing can also be done at the connected AS-Interface master which is supported by different manufacturers.