SDM-SIO1 Serial Input/Output Module
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The SDM-SIO1 Module is implemented in such a way that it looks like a built-in
serial port to the user when writing programs in CRBasic. This means all the user
needs to do is define the address of the SDM-SIO1, which is easily accomplished
by the use of a rotary switch on the side of the unit. The serial port can then be
used as if it were built into the datalogger. The only difference in operation
between the SDM-SIO1 and a built-in port is that there will be a small delay when
transferring data to and from the device via the SDM connection (see Section 4.1).
The SDM-SIO1 can also be used in `talk-through’ mode to allow a user to talk, via
a terminal module, to a sensor connected to the SDM-SIO1 for test and diagnostic
purposes. Please refer to the logger manual for further details.
Section 4 of this manual gives the differences in the use of this module compared
to the datalogger standard serial ports, plus there are some simple examples.
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Specifications
2.1 Supported data rates and protocols
Data rates and protocols are set up using the SerialOpen command in CRBasic.
The SerialOpen command is discussed elsewhere in this document.
Supported data rates
300, 1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200 bits/s
Supported modes of operation
RS-232 (Full duplex and receive only), RS-485 (Half and full duplex), RS-
422 (Half and full duplex). Hardware CTS/RTS flow control is supported in
RS-232 mode, the handshaking lines can also be used as general purpose I/O
lines.
Supported data format
8, 7 bit data size*; none, odd or even parity; one or two stops bits.
* In 7 bit mode with no parity the user must ensure that the characters
received by the SDM-SIO1 have a delay of at least one bit period or
greater between them. This does not affect any other configuration and
does not affect transmissions out of the SDM-SIO1.
Miscellaneous information
The SDM-SIO1 does not support auto baud rate detection nor the use of
the serial port for DNP, or general PakBus communications.
Use of the serial port for general Pakbus communications is not currently
supported.
Buffer sizes
Transmit buffer size: 767 Bytes (Buffer from the logger to the sensor)
Receive buffer size: 2047 Bytes (Buffer from the sensor to the logger)
Both transmit and receive buffers are fill and discard type, i.e. once the
buffers become full no new information is accepted and all further data is
