Cable Specs:
- 22 AWG with (1) Twisted Pair + 1 Conductor Shielded
- Plenum rated where required
- Impedence of between 100 and 130 ohms
- Capacitance between conductors of less than 30 pF per foot (100 pF per meter).
- Capacitance between conductors and shield less than 60 pF per foot (200 pF per meter)
Installation Requirements
- Trunks may be up to 1000 ft., but 500 ft. or less is recommended.
- Check specifications on max device count per trunk. In general, we recommend no more than 32 per trunk.
- Repeaters are not recommended.
- 120 OHM resistor at each end of the trunk across the receiver (+ and - terminals). Do not terminate resistor in third (ground) wire or on shield.
- Butt splice shield/drain at each location
- Butt splice and tape common reference/ground where common terminal is not available
- Ground shield/drain at one end only.
- RS-485 is polarity sensitive.
- Ungrounded end of the drain must be wrapped with at least 4 rotations around cable casing and taped with 2 wraps. Do not cut the drain short in the casing.
- Must be wired in point-to-point daisy chain fashion. No T-taps, stubs, spurs, or stars.
- May not share conduit with 120v+ cabling.
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