HF scientific Micro200BW Turbidimeter - 0 -1000 NTU - Manual (Page 50)

Page 36
MICRO 200 BW 0 - 1000 NTU (5/05)
Rev. 3.1
between the most remote MICRO 200 BW analyzer and
the host computer does not exceed 50 feet (16.4 m.).
Due to it’s “tri-state transmitter” design, the companion
MICRO 200 BW units, which are on the same serial
port at the host computer, may be “hubbed” or con-
nected each one to the next as long as the total cable
length from each MICRO 200 BW to the host computer
does no exceed 50 feet (16.4 m.). See figure 23 on page
41.
TXD = Pin #1; Transmitted data out; Data to computer
or printer
GRD = Pin #5; ground; digital common
RXD = Pin #8; received data in; data from computer to
MICRO 200 BW
SHIELD = PIN #4
Please consult HF scientific, inc. for more detailed
instructions.
2. RS-232 Current Mode Interface
(Catalog # 19862)
This configuration is used where the cable length
between the most remote MICRO 200 BW analyzer
and the host computer exceeds 50 feet (16.4 m.).
Because it is sensitive to the resistance of the intercon-
necting cable, and because each interface used causes
the total loop resistance to increase, it’s use is limited to
only a few stations. It is difficult to determine how
many stations may be used until all of the geographic
site locations are determined. Please consult HF scien-
tific, inc. if this option is under consideration. A more
prudent choice might be the RS-485 option, the de-
scription of which follows this. See figure 24 on page
41.
3. RS-485 Half Duplex Interface
(Catalog # 19851)
This option may be used where the distance from the
host computer to the most remote MICRO 200 BW
analyzer is, in extreme cases, up to 10,000 feet (3.28
km), depending on the site noise conditions. It is
similar to the RS-232 Standard Voltage Mode Interface
except that it transmits in a “Balanced” mode, in one
direction, at one time (half-duplex). This balanced
mode makes it less susceptible to noise. It also maybe
“hubbed” or connected each one to the next. It is
important the most remote interface, and only it, should
have it’s switch “closed” to properly terminate the
network. Please consult HF scientific, inc. for more
specific information. See figure 25 on page 41.
4. Serial Printer (Catalog # 19860)
This options provides a printout every 4 hours, or every
24 hours at midnight, of: date, time of period, mini-
mum NTU, average NTU, and maximum NTU read-
ings during the selected period. The printer option is
supplied in a NEMA 4x enclosure intended for wall
mounting. This option is shipped with an instruction
manual addendum giving more detailed information on
installation and operation. Please consult HF scientific,
inc.. for more specific information.