Campbell PVS5120 Series, Инструкция по эксплуатации

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PVS5120-Series Portable Samplers
50
•
Tries – The Tries parameter is used to specify the number of times the
ModbusMaster datalogger should attempt to communicate with the
SlaveModbus
datalogger before moving on to the next instruction.
• TimeOut – The TimeOut parameter specifies the amount of time, in
0.01 seconds, that the ModbusMaster datalogger should wait for a
response from the ModbusSlave before considering the attempt a
failure.
For more information on each of the ModbusMaster() parameters, see
CRBasic Help . Section 8.2.5.5 , Modbus® Example Instructions
(p. 50)
, provides
some example ModbusMaster() instructions. Complete program examples for
the CR1000 can be found on our website at www.campbellsci.com/19_1_767
and in Appendix B.3 , Modbus® Example Programs
(p. B-6)
.
8.2.5.5 Modbus® Example Instructions
This instruction initiates a sample and uses
Function 15
to set the flag in the
sampler:
ModbusMaster( MbResult(2),ComSDC7,38400,MBAddress,15,Start_sample,1,
1,3,100,0 )
This instruction checks to see if the sampler is still running:
ModbusMaster(
MbResult(1),ComSDC7,38400,MBAddress,1,Start_sample,1,1
,3,100,0 )
This instruction collects the status values:
ModbusMaster(
MbResult(3),ComSDC7,38400,MBAddress,3,Sampler_status(),
23,4,3,100,0
)
8.2.6 Pulse Control
The sampler can be directly connected to a 0 to 5 V TTL pulse outputting
device via the PVS5120CBL control cable. The sampler counts the
accumulating pulses from the external device, for example a flow meter, to
trigger a sample.
The sampler monitors either a 5 V contact closure or a positive pulse
waveform. Either type of pulse needs to generate at least a 50 ms pulse width.
When running the sampler via pulse control the four status values will not be
returned to the user unless monitoring the sampler via RS-485 (similar to time-
based control). See Appendix C , Monitoring Sampler Status via RS-485
(p. C-1)
to learn how to configure for RS-485 monitoring.
If using a datalogger, it may be easier to wire the pulse output
device (flow meter or rain ga u ge) to the datalogger, and then
have the datalogger monitor and record the pulses. The
datalogger can control the sampler via SDI-12 or RS-485 and
return the four status values to the user.
NOTE