Campbell MD9 Bedienungsanleitung PDF herunterladen (Seite 2)

MD9 Network Configuration

Each MD9 network requires:

1) User-supplied IBM-compatible

computer, -PC or greater.

LoggerNet Software recommended.

2) RS-232 serial cable. SC25PS for

25-pin serial ports; 7026 for 9-pin serial

ports.

3) SC532(A) Interface. Converts to RS-232 logic.

4) SC12 9-pin Serial Cable; provided with MD9.

5) MD9 CT Coax Terminator (75 Ohm). Sold in pairs; one required at each end of cable.

6) BNC "T" connectors. Provided with MD9.

7) MD9 Multidrop Interface. One at computer and one at each datalogger in the network.

8) User-supplied coaxial cable. RG59/U (Belden Model #9100 recommended). Requires user-attached BNC

connector at each junction. Alternatively, completed "sections" of cable or RG59/U cable (cut to length) and

BNC connectors can be ordered from Campbell Scientific.

9) CSI's CR510, CR500, CR10(X), 21X, CR23X or CR7. A 12 Vdc power supply is required; an environmental

enclosure is typically used.

Network Design Considerations

Signal loss due to the number of MD9's, the cable, and the coax terminators affects the quality of the communi-

cation signal. To maintain a signal suitable for data transmission, the network signal loss cannot exceed 50 dB.

The signal is attenuated 0.2 dB by each MD9 and 6 dB by the terminator pair. Signal loss due to the cable varies

with cable type and quality. Typically, cables with low attentuation are more expensive.

Example:

For a system with 100 MD9s, the MD9s introduce an attenuation of:

MD9 attenuation = (number of MD9s) (0.2 dB)

= 100 x 0.2 dB

= 20 dB

The two terminators add another 6 dB loss. Because the network signal loss cannot exceed 50 dB, the signal loss

of the cable cannot exceed:

Cable loss = 50 dB - (20 dB + 6 dB)

= 24 dB

If a cable with an attenuation of 0.6 dB/100 ft is used, the maximum cable length that can be used is:

Max length = (24 dB)/(0.6 dB/100 ft)

= 4000 ft

SC532

MD9

Datalogger

MD9

Datalogger

MD9

Datalogger Datalogger

MD9

MD9 CT

Cable branches

<10 feet in length

are acceptable.

MD9 CT

RS-232 Cable

SC12 Cable

Coax Cable

SC25PS

BNC & BNC "T" Connector

1 2 3 4

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