A4: Digital And Analog Nc I/O For Sinumerik 840D Sl; Introduction - Siemens SINUMERIK 840D sl Function Manual

A4: Digital and analog NC I/O for SINUMERIK 840D sl

2.1

Introduction

Functions
I/O modules can be connected to a SINUMERIK 840D sl via PROFIBUS or PROFINET.
Normally, the PLC user program uses the appropriate digital or analog inputs and outputs for
access. The "Digital and analog NC I/O for SINUMERIK 840D sl" function enables access to
the inputs/outputs of the I/O modules via system variables of compile cycles directly from the
NC (part programs, synchronized actions and compile cycles). This I/O is referred to as the
NC I/O in the following.
Three different functions are available for compatibility reasons:
1. Direct I/O access without PLC (Page 59)
Avoiding the PLC, the control internal images of the inputs/outputs of the I/O modules can
be accessed directly from the NC.
This is currently the function with the highest performance with regard to the quantity
structure and response time.
2. Direct I/O access via PLC (Page 54)
The read and write requests of the inputs/outputs of the I/O modules are written from the
NC via the interface to the PLC. An interrupt is then triggered on the PLC. The requests
from the PLC are processed as part of the interrupt processing.
From the quantity structure, the function is equivalent to that described above. However,
the response time is not as good.
3. Indirect I/O access via PLC (Page 30)
The read and write requests of the inputs/outputs of the I/O modules are written from the
NC via the interface to the PLC. The requests are processed cyclically in the OB1 cycle.
This function has the lowest performance with regard to the quantity structure and response
time.
Requirements
● The PROFIBUS/PROFINET I/O modules of the NC I/O must be connected and ready to
use.
● The HW configuration of the PROFIBUS/PROFINET I/O modules of the NC I/O has been
performed with the SIMATIC S7 Manager or HW Config and loaded to the PLC.
Extended Functions
Function Manual, 10/2015, 6FC5397-1BP40-5BA3
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