Maintenance for 2001N, 2002N, and 1800R Manual
Technical Notice
Wiring
• When using a dedicated instrument ground, the resistance to ground should be less than 1 ohm.
Use stranded wire for best noise immunity, of sufficient gauge to keep the resistance low. For
example, at least 18 AWG (1.02 mm) wire would be required for a distance of 150 feet, or 10 AWG
(2.6 mm) for 1000 feet.
• Since instrument common terminals 25, 16 and 41 are all internally tied together, 16 and 41 will also
be tied to ground when terminal 25 is connected to ground.
• If necessary, use a “pigtail” wire from the terminal and splice it to multiple common or shield wires.
• Spliced wires should be twisted before applying a crimp connector.
• All ground wires should be kept as short as possible.
• DO NOT use the wire’s shield for a signal or common.
• Analog input signal wiring must be at least 22 AWG (0.65 mm), though larger is perferred.
• Wire Recommendations:
Stranded shielded twisted pair wire should be used for all signal and communication wiring. The wire
should have a minimum of a 2-inch lay (6 twists per foot). It is best for each pair to have its own
shield. If using multiple pairs that share a shield, do not mix high and low voltage signals within the
same shield.
• I/O Signals
• At least 22 AWG (0.65 mm), though larger is perferred
• Remote I/O Communications
• Up to 1600 ft (500 m) 24 AWG (0.51 mm) overall foil shield and drain wire
(Beldon 9841 or equiv.)
• ICN Communications
• Up to 500 ft (150 m) 18 AWG (1.02 mm)
• 500-1500 ft (150-460 m) 18 AWG (1.02 mm), 18-25 pf/ft (60-83 pf/m)
• 1500-2000 ft (460-610 m) 22 AWG (0.64 mm)
• RS-232 Communications
• Up to 50 ft (15 m) virtually any standard shielded twisted pair with drain
(Beldon 9502 or equivalent)
• RS-422 and RS-485
• Up to 20 ft (6 m) virtually any standard shielded twisted pair with drain
• 20-1000 ft (6-305 m) 24 AWG (0.51 mm) overall foil shield and drain wire
(Beldon 9841 for 2-wire and 9502 for 4-wire, or equiv.)
• 1000-4000 ft (305-1220 m) 24 AWG (0.51 mm) overall foil shield and drain wire on each pair
(Beldon 9841 for 2-wire and 9729 for 4-wire, or equiv.)
Topic: MOD 30ML/Modcell Technote: TNML1001-1
MicroMod Automation, Inc. Rev. 3, Feb-2005
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