Commissioning The Physical Interface - Siemens SIMATIC CP 440 Manual

Commissioning the CP 440
3.2

Commissioning the Physical Interface

If there is no communication with the partner device after configuration has been
completed, you should test the connection. To do this, proceed as follows:
1. What might be the possible cause:
– Is the polarity of the send/receive lines reversed?
– Are the default settings correct? Several defaults may have been set with
different polarity. The default settings may already be integrated in the
device on a permanent basis.
– Incorrect or missing terminating resistors?
– High byte and low byte mixed in the security word (e.g. CRC)?
2. How to proceed:
– First of all use the manual to check the line connection:
– Assignment (Appendix B)
– Polarity (Appendix B)
– Default settings (Section 5.3)
– Carry out a setup test
3. Carry out the simplest setup possible:
– Connect only 2 nodes to each another
– If possible, use 2-wire cable (RS485)
– Use a short connecting cable
– Terminating resistors are not required due to the short distance
– Send first in one direction and then in the other
4. Check:
Always monitor the TXD send and RXD receive LEDs during the following
operations:
Example 1: The polarity of the line is definitely correct
– The default settings (all options) vary
– Check the security word (e.g. CRC)
Example 2: The default settings are definitely correct
– Reverse the connections (note: cross both pairs of lines in the RS422)
– Check the security word (e.g. CRC)
3-4
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02