Siemens SIMATIC CP 440, Руководство пользователя

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Commissioning the CP 440
3-4
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
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)