Module Integration Manual
Page 8 of 18
Interrogator RF Board (400.00152.xxxx)
4
C
OMMUNICATION
P
ROCESSOR
All host activities are routed through the communications processor. This processor supports
COM0, COM1, and I2C external communications and manages internal communications with
the DSP.
4.1
COM0
(SCADA)
By default, COM0 is a half-duplex serial port intended to drive an isolated RS485 transceiver.
The signals are 3.3V CMOS levels. TE0 is controlled by the communication processor to
enable transmissions on an RS485 bus. When operated in half-duplex the module assumes it
will see a replica of TX0 bits on RX0, so the receive enable line of the RS485 adapter should
always be on.
If COM0 will be used for CMOS level communications with another
processor on the host, e.g. embedded into a meter, then the EEPROM
settings should be altered to make COM0 be full duplex or the host should
echo all characters back to the INTERROGATOR RF BOARD.
COM0 supports baud rates of 4800, 9600, 19200, 38400, 57600, and 115200. The port
supports one or two stop bits and supports odd, even, or no parity.
COM0 can support the IS485 proprietary command language (NATIVE) or MODBUS-RTU.
COM0 only responds to transmissions with a matching address, which can be between 1 and
247.
4.2
COM1
(D
IAGNOSTICS
)
COM0 is restricted to full duplex, 115200 baud, no parity, one stop bit, and NATIVE commands
with an address of 1. This port should be connected to an FTDI 282R USB to serial chip so that
IntelliSAW applications may directly access the INTERROGATOR RF BOARD core. This will
facilitate setup and diagnostics. To be compatible with future upgrades, the FTDI 282R chip
should also route CUSB2 to the SPARE pin of the connector, although the function of this pin
has not been selected.
4.3
I2C
(S
LAVE
S
ENSOR
)
The I2C port supports Sensirion® SHT-11 humidity sensors. The host system should provide
sufficient ESD and EST protection for a wired sensor if humidity and ambient temperature
measurements are desired. This sensor is automatically measured as a background task and
the results are presented in MODBUS registers. The maximum baud rate is 300.
4.4
C
OMMAND
P
ROCESSING
The communications processor has multiple levels of privilege determined by passwords.
OEMs will be provided with the passwords suitable to the commands they need to access and
the documentation for those commands. Commands fall into one of four categories:
