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CDM-A100 Series
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
NextScan
EndProg
8.2.2 CPI Network Bit Rate
28
BurstSETable
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
). This is the rate that data are transferred from the CDM
(p. 21)
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
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
1
Bit Rate
(kbps)
Full Termination
1000
500
250
125
50
1
Default Bit Rate is 250 kbps. Change with CPISpeed() instruction.
8-2
for the maximum cable length allowed
Maximum Total Cable Length (ft)
Daisy-Chain Topology
Half Termination
50
1
200
200
500
400
1200
1000
2800
2400
Star Topology
No Termination
not viable
100
400
1000
2400
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