3–24 469 MOTOR MANAGEMENT RELAY – INSTRUCTION MANUAL
CHAPTER 3: INSTALLATION
FIGURE 3–26: Alternate Wiring for Contactors
3.2.11 Drawout Indicator
The Drawout Indicator is simply a jumper from terminals E12 to F12. When the 469 is
withdrawn from the case, terminals E12 and F12 are open. This may be useful for
differentiating between loss of control power as indicated by the 6 SERVICE relay and
withdrawal of the unit.
3.2.12 RS485 Communications Ports
Two independent two-wire RS485 ports are provided. Up to 32 469s can be daisy-chained
together on a communication channel without exceeding the driver capability. For larger
systems, additional serial channels must be added. Commercially available repeaters can
also be used to add more than 32 relays on a single channel. Suitable cable should have a
characteristic impedance of 120 Ω (e.g. Belden #9841) and total wire length should not
exceed 4000 ft. Commercially available repeaters will allow for transmission distances
greater than 4000 ft.
Voltage differences between remote ends of the communication link are not uncommon.
For this reason, surge protection devices are internally installed across all RS485 terminals.
Internally, an isolated power supply with an optocoupled data interface is used to prevent
noise coupling.
Note
To ensure that all devices in a daisy-chain are at the same potential, it is imperative
that the common terminals of each RS485 port are tied together and grounded only
once, at the master. Failure to do so may result in intermittent or failed
communications.
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