Automation Direct D2-DCM, Руководство пользователя

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Building the Cable
12
Data Communications Module, 2nd Edition, 2/03
Although many types of cables may work for your application, we recommend you
use a cable that is constructed to offer a high degree of noise immunity. A cable
constructed equivalent to Belden 9855 is sufficient. The following specifications are
to be used as a guideline.
Structure Shielded, twisted-pair . . . . . . . . . . . . . . . . . . . . . . .
(RS232C only uses two wires and a ground)
Conductor size 24 AWG or larger . . . . . . . . . . . . . . . . .
Insulation Polyethylene . . . . . . . . . . . . . . . . . . . . . .
Shield Copper braid or aluminum foil . . . . . . . . . . . . . . . . . . . . . . . . .
Impedance 100
W
@ 1MHz . . . . . . . . . . . . . . . . . . . . .
Capacitance 60pf / meter or less . . . . . . . . . . . . . . . . . . . .
Your company may have guidelines for cable installation. If so, you must check those
before you begin the installation. Here are some general things to consider.
D
Don’t run cable next to larger motors, high current switches, or
transformers. This may cause noise problems.
D Route the cable through an approved cable housing to minimize the risk
of accidental cable damage. Check local and national codes to choose
the correct method for your application.
D
Consider redundant cabling if the application data is critical. This allows
you to quickly reconnect all stations while the primary cable is being
repaired.
Cable Shield Grounding — It is important to ground the cable shield to minimize
the possibility of noise. The preferred method is to connect one end of the cable
shield to the connector housing. If noise problems are still present and you have a
good earth ground for the cabinet, you must connect one end of the shield to the
cabinet earth ground.
Don’t ground both ends of the shield because this will create
induced noise on the cable.
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
2.5”
Step 1: Strip back about 2.5” of the shield.
Step 2: Crimp a ring connector onto the shield.
Step 3: Secure the shield to
the connector shell.
Consideration 4:
Cable Specifications
Consideration 5:
Installation
Guidelines