34 of 35 REF: CCU3/C-4100.DOC REV: M September 26, 2005
Figure 34: Confirmation window
Close the reprogramming window. Make sure the Version number is changed in
the main CCUNet window.
Appendix B. Cabling
Recommendation
All cables should be copper or tinned copper twisted pair.
All conductors must be 18AWG to 24AWG.
The maximum resistance for each conductor must be less than 140 Ohms over the
entire length.
The maximum capacitance between 2 conductors in a twisted pair must be less than
70nF over the entire length.
TX+ and TX- must be connected as a pair through the cable to RX+ and RX- at the
other end.
RX+ and RX- should have a terminating resistor of 100 Ohms connected between
them especially for long hauls.
Cable lengths of up to 1km may be reached by using appropriate, good quality cable.
Cables run through noisy environments (such as power stations, near heavy
machinery or close to high power cables) may require shielding, to ensure
communication with a low error rate. If shielded cable is used, the shield should be
connected to the Earth pin at both ends.
The CCU3 has surge protection on all serial communications ports and has been
tested to IEC 61000-4-5, however, this protection is not intended to protect from a
direct lightning strike or from contact with high power lines. All cables run outdoors or
in other environments susceptible to lightning strikes or exposure to high powered
lines should have external low capacitance primary protection installed. Using earthed
shielding is suggested in these applications for safety reason.
Generally the 0V pin connection is not connected. In very noisy environments, it may
be necessary to use cable that has individually shielded pairs as well as an isolated
outer cable shield. In these circumstances connect the 0V pins at either end through
the individual pair shields and connect Earth to the outer cable shield. This will
provide the maximum signal to noise ratio.
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