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Technical notice – Micromod MOD: 30ML and Modcell Maintenance for 2001N, 2002N, and 1800R User Manual

Page 143

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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

GroundingWiring.doc

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