Electro Industries/GaugeTech Nexus 1250, Руководство по установке и эксплуатации

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Electro Industries/GaugeTech
Doc #: E107-7-06-121
9-2
9.2: Installing Nexus External I/O Modules 9.2: Installing Nexus External I/O Modules
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I/O modules must use the Nexus Monitor’s port 4. Port 4 allows the Nexus Monitor, normally a
slave, to become a Master (Port 3 can be used as an alternate). Six feet of RS-485 cable harness is
supplied. Insert one end of the cable into port 4; insert the other end into the module’s Male RS-485
Side Port. The connectors fit only one way into the ports. See section 9.3 for details on using
multiple I/O modules.
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The Nexus Monitor will power up to four modules ( two Analog Output Modules) using 15–20 VDC
at 50–200 mA, represented by dashed lines in the figure below. Refer to sections 5.12 - 5.13 for the
steps to determine if you must use an
additional power source , such as the EIG Power Brick
(model #PB1, 12V). RS-485 communication is capable for up to 4000 feet (1219 meters). However,
if your cable length exceeds 200 feet, use the additional power supply and:
•
Connect the A(+) and B(-) terminals on the Nexus to the A(+) and B(-) terminals of the male
RS-485 port. Connect the shield to the shield (S) terminal. The (S) terminal on the Nexus is used
to reference the Nexus port to the same potential as the source. It is not an earth ground
connection. You must also connect the shield to earth-ground at one point.
•
Provide termination resistors at each end, connected to the A(+) and B(-) lines. RT is
approximately 120 Ohms.
+ V - S B(-) A(+)
A(+) B(-) S - V +
Figure 9.2: Nexus Monitor Connected to I/O Module
RT
RT
Male Side Port on Nexus I/O Module
Nexus Monitor
Port 4
LED’s
Courtesy of NationalSwitchgear.com