Campbell CDM-A100 Series, Instruction Manual

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CDM-A100 Series
28
CRBasic Example 8-2. Measuring VoltSE() in Burst Mode
'Program Example
Public BurstSE(1735)
DataTable (BurstSETable,True,-1)
Sample (1735,BurstSE(),FP2)
EndTable
BeginProg
Scan
(1,sec,10,0)
‘Negate the measurement channel to make a burst measurement
CDM_VoltSe (CDM_A108,1,BurstSE(),1735,mV5000,-1,False,150,15000,1,0)
CallTable BurstSETable
NextScan
EndProg
8.2.2 CPI Network Bit Rate
A CPI network is capable of operating at 1000, 500, 250, 125, or 50 kbps,
depending on your network configuration (see Section
7.6 , Connecting
Multiple CDMs
(p. 21)
). This is the rate that data are transferred from the CDM
to the datalogger. When multiple CDMs are making measurements faster than
1 Hz, it is important to ensure that the CPI network bit rate is higher than the
rate that data is generated by the CDMs within the network.
To calculate how many kilobits per second (kbps) will be generated, use the
following equation for each CDM in your network:
Equation 8-1: Kilobits per second = (number of measurements) ×
(measurement frequency) × (0.064 kilobits per measurement)
The network topology and cable length affect the maximum allowable CPI
network bit rate. Refer to TABLE
8-2 for the maximum cable length allowed
for the topology and bit rate your network requires. The bit rate of the network
defaults to 250 kbps and can be changed by using the CPISpeed() instruction
in the datalogger program.
TABLE 8-2. 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.