GE Hydran 201i, Instruction Manual

Page: 185 / 300

Local Network Installation
Part 17997 Rev. 6, March 2011 9-9
9.5.1 Installing an RS-485 Local Network Link Between Hydran 201C
i
Controllers
A local network is a chain of Hydran 201 i Systems and/or Hydran 201R Model i ’s in which
the Hydran 201C i Controllers are connected together using an RS-485 link. If the instal-
lation includes only one Hydran 201 i System or Hydran 201R Model i , go to Section 9.5.2
on page 9-10.
Proceed as follows:
1. Run an RS-485 cable from one H201C i to the next in a conduit to form a chain. Use
instrumentation-grade cables (twisted triad with overall shield); otherwise use
armored cables.
Note: The total maximum length for all RS-485 link cables in a local network is 1,200 m
(4,000 ft).
2. Connect the RS-485 cables into the main terminal block. For wiring details, see
Appendix D.
Note: No wires are criss-crossed in an RS-485 link; pin 1 is always connected to pin 1,
pin 2 to pin 2, pin 3 to pin 3. Except for the two H201Ci’s located at each end of a local
network, two RS-485 link cables are attached to each H201Ci using the Main Terminal
Block. Powering down one H201Ci does not affect the local network nor the other
H201Ci’s.
CAUTION
WARNING
The shield of each cable section must be grounded at one end only.
CAUTION
WARNING
The shield of each cable section must be grounded at one end only.
Routing and shielding of the RS-485 cable is particularly important
because all H201Ci’s belonging to a network share a common
reference with this link.
CAUTION
WARNING
The operation of the complete H201Ci network may be affected if
wires are not connected correctly. Be careful when installing and
inserting each wire. Be sure to insert all strands in the terminal;
strands that touch two terminals cause problems. Do not leave trims
of metallic strands inside the H201Ci’s enclosure.