Campbell TEMP 120, Product Manual

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Table 10-1: Network topology, bit rate, and cable length
Bit Rate
1
(kbps)
Maximum total cable length (ft)
Daisy-chain topology Star topology
Full termination Half termination No termination
1000 50 1 not viable
500 200 200 100
250 500 400 400
125 1200 1000 1000
50 2800 2400 2400
1
Default Bit Rate is 250 kbps. Change with
CPISpeed()
instruction.
10.5 Multiple devices
Multiple GRANITE Measurement Modules may be connected to a single data logger using a
daisy-chain or star topology (see
Connecting multiple GRANITE Measurement Modules (p. 17)).
In both network configurations, as total cable length increases, the maximum possible bit rate
decreases. Limitations on cable length and baud rate are examined in the document
Designing
Physical Network Layouts for the CPI Bus .
When including two or more TEMP 120 devices in the program, the processing mode of the data
logger affects the measurement timing of each TEMP 120. In sequential mode, the TEMP 120
devices make measurements one after the other, following the order of their instructions within
the program. Conversely, in pipeline mode, the devices start their measurements simultaneously.
Pipeline mode is recommended.
11. Maintenance and calibration
l
Protect the TEMP 120 from humidity and moisture.
l
Send to Campbell Scientific for factory calibration every three years.
If sending the TEMP 120 to Campbell Scientific for calibration or repair, consult first with a
Campbell Scientific representative. If the TEMP 120 is malfunctioning, be prepared to perform
some troubleshooting procedures with Campbell Scientific. Many problems can be resolved with
TEMP 120 23