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Kohler — Wire the RSA III

Installation

From a Kohler service manual covering: APM402, APM603, APM802, Decision-Maker 550, GM32644-KP1, GM62466-KP1, GM91356, KPC 1000, MPAC 1000, MPAC 1200, MPAC 1500, MPAC 750. Check it applies to your exact model before use.

Applies to: Kohler APM402, Kohler APM603

Before you start

  • Isolate the RSA III leads from all other voltages.
  • Use separate conduit and grounded metallic conduit or shielded cable in nonmetallic conduit.
  • When using RS-485 communication cable, connect the shield wire at either end but not at both ends.

Procedure

  1. Disconnect the 12/24-volt DC power source to each RSA III.
  2. Connect RS-485 wiring from the controller to P27 of the RSA III master using Belden #9841 or equivalent.
  3. Connect RSA III master to slave(s) in a daisy chain configuration on P27.
  4. Set the P34 termination resistor position based on the number of Modbus devices on the network.
  5. Connect 12/24 VDC power (200 mA min.) to P37 from the engine starting battery; positive lead should be fuse protected.
  6. Set the P39 isolated/non-isolated jumper for the application.
  7. Connect alarm horn and common fault dry contacts to P40.
  8. Make local (hardwired) EPS and user-defined digital input connections on P41 and P42.
  9. Connect remote user-defined digital inputs to the controller customer connection terminal block.
  10. Document the user-defined digital inputs on the RSA III front panel strip.
  11. Assign the RSA III connected to the controller as the RSA III master.
  12. Replace any controller covers, hardware, and access panels.

Specs & values

  • P27 RS-485 Amazon eBay $499.00 FridayParts $92.25: P27-1 (-) Black, P27-2 (+) White, P27-3 Shield, P27-4 (-) Black, P27-5 (+) White, P27-6 Shield
  • P37: P37-1 Ground, P37-2 12/24 VDC battery input (not polarity sensitive), P37-3 12/24 VDC battery input (not polarity sensitive)
  • P40 dry contacts rated 220 VAC @ 0.8 amps and 30 VDC @ 2 amps
  • Wire gauge vs. length: 0-137 m (0-450 ft.) = 22 AWG; 137-213 m (450-700 ft.) = 20 AWG; 213-343 m (700-1125 ft.) = 18 AWG; 343-549 m (1125-1800 ft.) = 16 AWG; 549-853 m (1800-2800 ft.) = 14 AWG
  • Use solid or stranded 14-22 Amazon eBay gauge wire

Source: Kohler service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.

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