Campbell Scientific LoggerNet Datalogger Support Software - Manual (Page 458)

Section 13. Implementing Advanced Communications Links
To begin, add a Serial Port to the device map if one does not exist. Add a
Phone Modem to the Serial Port. To this Phone Modem, add a Remote Phone
Modem. Next, add an MD9 base and then a remote MD9. To complete the
network, add your datalogger to the remote MD9. Review all of the settings
for each device, and make any changes to customize the settings for your
network configuration.
13.2.2 Operational Considerations
13.2.2.1 Scheduled Data Collection
The intervals for scheduled data collection need to set up to allow time for the
communications link to be established. Keep in mind that the phone modem
requires 15–20 seconds to dial and establish communication. Some time is
also required to close down the link before another station can be contacted.
Make sure the collection schedule allows enough time for each station to be
contacted before contacting the first station again.
13.2.2.2 MD9 Addresses
The address for an MD9 base device is set in the LoggerNet communications
software at 255. The hardware configuration in the MD9 base modem must
match for successful communications (refer to your MD9 users manual for
information on setting the hardware switches within the device). In addition,
the address specified in Setup for the MD9 remote modem must match its
hardware configuration.
13.2.2.3 Extra Response Time
LoggerNet is pre-programmed to expect certain response times from devices
depending on the type of intermediate devices and the communication rates
chosen. If the datalogger network communications link is marginal, it may
take longer to negotiate communication between the devices. Extra response
time added to one or more of the devices may help to prevent the software
from timing out. Note that the extra response times added for each device are
cumulative for the entire communications link, and the total response time
includes the default times plus any extra response time that has been added.
13.2.2.4 Max Time Online
The Max Time Online setting is used to force LoggerNet to terminate a
connection if the maximum time limit is exceeded. This is used to prevent a
phone modem from getting stuck online and incurring extra long distance
phone charges or inhibiting scheduled data collection from other stations. In
phone to MD9 systems this value should be long enough to allow data
collection for the anticipated amount of data. If the Max Time Online is
reached, LoggerNet will force the connection to close, even if it is in the
middle of collecting data.
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