FNCC device

The FNCC Tango device reflects the state of the Field Node Communications Controller. The following read-only attributes are exposed:

Tango attribute name	Register address(es)	Register description
ModbusRegisterMapRevisionNumber	1	Modbus FNCC register map revision number, fixed at firmware compile time
PcbRevisionNumber	2	FNCB revision number, fixed at firmware compile time
CpuId	3-4	Microcontroller device ID
ChipId	5-12	Microcontroller unique device ID
FirmwareVersion	13	Firmware revision number, fixed at compile time
Uptime	14-15	Time, in seconds, since FNCC boot
SysAddress	16	Modbus address
PasdStatus	17	Communications status (see below)
FieldNodeNumber	18	Field node unique ID (set using rotary switch)

The FNCC PasdStatus attribute should be interpreted as follows:

PasdStatus attribute value	Meaning
OK	System operating normally, all comms links open
RESET	Serial to ethernet converter being reset
FRAME_ERROR	UART3 framing error
MODBUS_STUCK	Timer circuit on FNCB tripped
FRAME_ERROR_MODBUS_STUCK	Both framing error and timeout have occurred

After an error has occurred, the status register is automatically reset by issuing the ResetFnccStatus() command on the MccsPasdBus. The number of resets is kept track of and can be read via the ResetCount attribute. This attribute can be reset by writing a zero to it.

The FNCC’s heath model reflects the current value of the status register. A value of ‘RESET’ translates to DEGRADED health, ‘OK’ to OK health, and everything else to FAILED health.