HF scientific CLX Online Residual Chlorine Monitor - Manual (Page 14)

CLX (1/12) Page 9
REV 5.1
Plugs are inserted into the RS-485 and 4-20mA cable bulkheads when shipped, to ensure a
watertight seal. These plugs should be removed and discarded when cabling to either of
these connections.
The power cable bulkhead will accept cable diameters from 5.8mm (.230 in.) up to 10 mm
(.395 in.). All terminals are designed to accept wires in the range of 14-28 AWG. All
wires should be stripped to a length of 6 mm (¼”). A strain relief strap is provided to
reduce tension on the power terminals.
It is the user’s responsibility to assure that a watertight seal is maintained after the CLX
has been wired for operation. If any of the bulkheads are not tightened properly around a
cable or plug, the ratings of the instrument will be jeopardized and there is a possibility of
creating a shock hazard.
Only qualified electricians should be allowed to perform the installation of the
instrument as it involves a line voltage that could endanger life.
4.3.1 Power
The instrument is equipped with 100-240 VAC, 47-63 Hz power supplies requiring
150VA; please verify that the line voltage falls within these specifications. It is
recommended that a circuit breaker be placed prior to the power connection to
allow for service. For safety it is recommended that the connection be less than 2
meters (six feet) from the instrument. While making connections, refer to Figure 5.
The CLX is intended for cord connection with a three wire non-locking grounded
power cord, however ridged or flexible conduit connections can be used. A power
cord can be purchased separately from the factory (Catalog No. 20779S). The
CLX is not supplied with a power cord. If the CLX is to be used in the U.S. or
Canada the power cord must be UL Listed & CSA Certified. Please consult all
local electrical codes for proper connection.
The connection block is marked N for Neutral and L for line the third symbol
indicates a secure earth ground. The green removable terminal block is suitable for
wire gauges 18 to 12 AWG.
4.3.2 RS-485
The RS-485 half-duplex (2-wire) digital interface operates with differential levels
that are not susceptible to electrical interferences. This is why cable lengths up to
3000 ft can be implemented. The last device on each bus may require terminating
with a 120 ohm resistor to eliminate signal reflection on the line. Do not run RS-
485 cables in the same conduit as power. Set-up of the RS-485 is covered in 7.3
Configuring the RS–485 Port
To prevent damage to the instrument, ensure that power is disconnected prior to
making connections. For ease of connecting, remove the plug-in terminal block.
Connections are labeled beside this termination on the PC board.
The recommended cable is 22 AWG shielded twisted pair. The grey terminal block
is removable to assist in making connections.