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8.
Troubleshooting and Maintenance
8.1
Troubleshooting
SDM-SIO1A and SDM-SIO4A Serial Input/Output Modules
FIGURE 7-1. RS-485 Internal Circuit Diagram
RG is for connecting the screen/ground of the data lines when in RS-485
mode; there is a 1 W 100 Ω resistor in series designed to limit any currents that
may be induced due to a difference in ground potentials between the sensor and
the SDM-SIO1A.
If correctly connected, the SDM-SIO1A normally operates seamlessly.
However, there are some common issues people encounter during setup or
sometimes after a period of operation.
During the setup phase, either no data or corrupt data may be received by the
datalogger. When receiving data, the character "?" will be returned in place of
the expected data whenever a parity, framing, or overrun error is detected.
These errors are only flagged for RS-232/RS-485/RS-422 data coming into the
SDM-SIO1A.
These types of errors are usually caused by a connection issue or sometimes a
mismatch of the interface type, baud rate, or data format (parity, etc.).
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