Enabling handshaking will increase active current consumption due to the extra RS-232 load. It
will not affect sleep current, however, as the RS-232 chip is disabled (sleep is set by calling the
SerialClose()
function).
For connection diagrams and further information on using handshaking, consult
examples for connecting the SDM-SIO2R
NOTE:
l
Auto flow control should only be selected in RS-232 mode.
l
When Auto flow control is enabled, the user cannot set or clear the spare I/O ports.
7.1.2 RS-485 half-duplex mode
In RS-485 half-duplex mode, the SDM-SIO2R will wait for approximately 2.5 ms after a character
is received before it tries to transmit any data in its transmit buffer. This is to ensure that a
contention does not occur on the data line which will cause data corruption. There is also a delay
of at least the time to send one character after the last character has been transmitted before the
SDM-SIO2R will listen for new incoming data.
NOTE:
When in either RS-485 half-duplex or full-duplex modes, the user cannot set or clear the
spare I/O ports (pins 8 and 11).
7.1.3 Using the RS-232 link in receive-only mode
To place the SDM-SIO2R into RS-232 receive-only mode, use the
SerialOpen()
instruction
with the
SerialOpenFormat
value set within the range of 64 to 79. Consult
27) for more detailed information about these settings.
In receive-only mode, the SDM-SIO2R will consume less current than normal but still can receive
new information on its RS-232 port.
The following example will set the SDM-SIO2R with address 0 into receive-only mode. All normal
baud rates and buffer sizes are supported.
Example
SerialOpen
(32,115200,64,100,10000)
'Set receive only mode
7.2 Power conservation
The SDM-SIO2R features an industry-standard RS-232/RS-485 driver chipset to ensure maximum
likelihood of compatibility with all other devices. When the driver is powered on, it uses more
SDM-SIO2R Serial Input/Output Module with Switched Sensor Power
35
