S5-95U, SINEC L2 Data Transmission Using Cyclic I/O
Updating the Cyclic I/O Input Area and Output Area
There is an exchange of ZP data (ZPA, ZPE, and ZP status bytes) between the control processor
and the communications processor at every cycle control point in the programmable controller's
CPU program cycle.
The communications processor transmits ZP data cyclically via the network independently of the
ZP cycle control point of the programmable controller’s CPU operating system.
There is complete data consistency for ZPA and ZPE.
SAP Number
A ZP slave can be addressed only if the ZP master knows both the ZP slave address and its
appropriate service access point (SAP).
You set the parameters for the ZP slave address and the ZP slave's SAP number in DB1 of the ZP
master.
If you are using an S5-95U as a ZP slave, the SAP number is 61: You must set the SAP
parameter in DB1 of the ZP master to 61.
If you are using a field device as a ZP slave, you can set the SAP parameter in DB1 of the ZP
master from 0 to 62. Refer to Appendix B for more detailed explanations and for a list of all SAP
numbers used with S5-95U programmable controllers.
Restart sequence when:
• powering up the PLC or
• switching the PLC from STOP to RUN following a "PLC overall reset" or
• switching the PLC from STOP to RUN after modification of the SL2 parameter block in
DB1
Before executing the restart OBs (OB21/OB22), ZPA and ZPE are assigned the default value "0" in
the ZP-DB. Bit 7 "ZP slave failure" or bit 7 "ZP master failure"in the STB is set ( section 7.3).
Restart sequence when:
• switching the PLC from STOP to RUN without modification of the SL2 parameter block
in DB1
ZPA is assigned the default value ”0” in the ZP DB before execution of the restart OB (OB21). The
input data presently available from the LAN are written to the ZPE in the ZP DB.
ZP Safety Function
When the programmable controller goes from RUN to STOP, ZPA and ZPE stay unchanged in the
ZP DB.
When the programmable controller is in the STOP mode, the value “zero” is sent as ZP output
data.
If a ZP slave fails, the ZP input bytes assigned to it in the ZP master are reset to 0. If a ZP master
fails, the ZP input bytes assigned to it in the ZP slave are reset to 0.
You can read out the status of all the ZP slaves by means of the ZP slave life list (see section 7.3)
EWA 4NEB 812 6112-02
7-3
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