other sources such as nearby mains cables. As a general rule, if you have a noise issue, it is worth
trying to add a cheap 100-120 Ω resistor across RS-485 lines.
8.2 Maintenance
No regular maintenance is needed for the SDM-SIO2R; however, occasionally operating system
upgrades are released to add enhanced features or to correct bugs. The operating system is
normally published in the Support section of our website at
.
8.2.1 Upgrading the operating system
In the unlikely event that the operating system of the SDM-SIO2R needs to be upgraded, this can
be achieved by connecting it to a computer and using the Campbell Scientific
Device
Configuration Utility
to load the operating system. (This program can be downloaded free of
charge from
).
The SDM-SIO2R needs a reliable source of 12V power connected in the standard way. It also
requires a cable similar to that shown in
Connecting a 9-way socket to the SDM-SIO2R for RS-
(p. 24) to connect to an RS-232 port on the computer. However, there is no
requirement to connect any handshaking lines.
Start
Device Configuration Utility
and select the SDM-SIO2R device. (The SDM-SIO2R device may
not be available in older versions of the software. New versions can be downloaded from the
Campbell Scientific website at
.) Follow the instructions for that device
to load a new operating system. At the end of the process, a success message will be shown if
successful. During the loading of the operating system, do not disturb or disconnect power to the
SDM-SIO2R, otherwise it may need to be returned to the factory for repair.
When following this process with the SDM-SIO2R, it is necessary to run this process two times,
connecting to each serial port in turn. This is because each serial port has its own microprocessor
with each holding their own copy of the operating system.
8.2.2 Operating system signature errors
The operating system is stored in flash memory. When a new version is loaded, a checksum
signature is automatically created the first time its run. This checksum is stored in memory. This
signature value can be read back using the data logger and compared to the signature supplied
with the operating system version that was just loaded (contact Campbell Scientific if you need to
do this).
If the SDM-SIO2R is not operational or is exhibiting random faults, the flash memory may be
corrupted. This is a very unlikely event due to the robust nature of the flash device used. The unit
automatically checks the flash memory against its signature upon power up. If an error is found, it
SDM-SIO2R Serial Input/Output Module with Switched Sensor Power
39
