Tecnetics Industries Tecweigh 20, Operation Manual

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4.00 Wiring Precautions
The following is a list of important precautions that should be observed during field wiring.
- Wiring should be compliant with all applicable electrical codes.
- Input power must be 100 to 240 VAC, 47-63 HZ, 60 watts.
- Only apply input power after assuring all wiring is correct.
- The electrical power source must be of utility quality and specification.
- Never splice wires. Replace short wires with one continuous length.
- Always run power wiring and signal wiring in separate conduits.
- Ground shield wires at only one location, usually the WP20.
- To prevent possible shorts, tape all shielded wire ends and keep the wiring neat.
- Use properly sized water tight compression fittings on cables entering the enclosure.
- Do not connect any wires to terminals designated as unused.
- Pay particular attention to proper grounding as depicted in the wiring diagrams.
4.01 Tecweigh 20 (WP20) Wiring
If the equipment at hand has been custom built by Tecweigh, you will find an “as built” wiring
diagram at the back of this manual. If it should happen to not be there, call the Tecweigh Service
Department (Section 2.01) to obtain a copy. Refer to sections 4.02 to 4.07 for more typical field
wiring diagrams. Some WP20 outputs can also be inter-connected with client supplied devices,
such as a totalizer or recorder, consult the field wiring diagrams provided with those specific
devices for further information. Section 6.02 defines the Parameter settings required to enable
the features of the outputs used.
Scale to WP20 wiring
Communications between the signal conditioner (SC) on the scale carriage and the WP20 is
accomplished using the industry standard RS485 communications protocol. At both ends,
terminal 10 is signal common, terminal 29 is 30 VDC power, and terminals 20 and 22 are A and
B channels of the communications signal. Use 18 gauge, two twisted pair, shielded cable
between the WP20 and the signal conditioner. Belden #1063A cable or equivalent is
recommended (25 ft. is normally provided by
Tecweigh on new installations, additional cable
can be obtained through Tecweigh ). If ordered direct from a Belden distributor, #1063A cable
has a standard color code of black and white for each twisted pair; one pair marked “1” the other
pair marked “2”. The two numbers are difficult to see in the field, so
Tecweigh instead stocks
#1063A cable with red/black and blue/yellow twisted pairs, which helps eliminate errors when
field wiring the scale.
Tecweigh’s field wiring diagram uses this color code, but if the #1063A is
not ordered through Tecweigh, it will be the dual black and white pairs.
IMPORTANT – Regardless of the brand of the two twisted pairs cable used, it is very critical
that one twisted pair be used for power (+DC & COM (also designated 29 and 10)) and the other
twisted pair be used for communications (RS485 A & B (also designated 20 and 22)).
CHAPTER 4 – SYSTEM WIRING