SYNC

Files
file	CO_SYNC.h
	CANopen Synchronisation protocol.

Data Structures
struct	CO_SYNC_t
	SYNC producer and consumer object. More...

Enumerations
enum	CO_SYNC_status_t { CO_SYNC_NONE = 0, CO_SYNC_RECEIVED = 1, CO_SYNC_OUTSIDE_WINDOW = 2 }
	Return value for CO_SYNC_process. More...

Functions
CO_ReturnError_t	CO_SYNC_init (CO_SYNC_t *SYNC, CO_EM_t *em, CO_SDO_t *SDO, CO_NMT_internalState_t *operatingState, uint32_t COB_ID_SYNCMessage, uint32_t communicationCyclePeriod, uint8_t synchronousCounterOverflowValue, CO_CANmodule_t *CANdevRx, uint16_t CANdevRxIdx, CO_CANmodule_t *CANdevTx, uint16_t CANdevTxIdx)
	Initialize SYNC object. More...
void	CO_SYNC_initCallbackPre (CO_SYNC_t *SYNC, void *object, void(*pFunctSignalPre)(void *object))
	Initialize SYNC callback function. More...
CO_ReturnError_t	CO_SYNCsend (CO_SYNC_t *SYNC)
	Send SYNC message. More...
CO_SYNC_status_t	CO_SYNC_process (CO_SYNC_t *SYNC, uint32_t timeDifference_us, uint32_t ObjDict_synchronousWindowLength, uint32_t *timerNext_us)
	Process SYNC communication. More...

Detailed Description

CANopen Synchronisation protocol.

For CAN identifier see CO_Default_CAN_ID_t

SYNC message is used for synchronization of the nodes on network. One node can be SYNC producer, others can be SYNC consumers. Synchronous TPDOs are transmitted after the CANopen SYNC message. Synchronous received PDOs are accepted(copied to OD) immediatelly after the reception of the next SYNC message.

Contents of SYNC message

By default SYNC message has no data. If Synchronous counter overflow value from Object dictionary (index 0x1019) is different than 0, SYNC message has one data byte: counter incremented by 1 with every SYNC transmission.

SYNC in CANopenNode

According to CANopen, synchronous RPDOs must be processed after reception of the next sync messsage. For that reason, there is a double receive buffer for each synchronous RPDO. At the moment, when SYNC is received or transmitted, internal variable CANrxToggle toggles. That variable is then used by synchronous RPDO to determine, which of the two buffers is used for RPDO reception and which for RPDO processing.

Enumeration Type Documentation

CO_SYNC_status_t

enum CO_SYNC_status_t

Return value for CO_SYNC_process.

Enumerator
CO_SYNC_NONE	SYNC not received.
CO_SYNC_RECEIVED	SYNC received.
CO_SYNC_OUTSIDE_WINDOW	SYNC received outside SYNC window.

Function Documentation

CO_SYNC_init()

CO_ReturnError_t CO_SYNC_init	(	CO_SYNC_t *	SYNC,
		CO_EM_t *	em,
		CO_SDO_t *	SDO,
		CO_NMT_internalState_t *	operatingState,
		uint32_t	COB_ID_SYNCMessage,
		uint32_t	communicationCyclePeriod,
		uint8_t	synchronousCounterOverflowValue,
		CO_CANmodule_t *	CANdevRx,
		uint16_t	CANdevRxIdx,
		CO_CANmodule_t *	CANdevTx,
		uint16_t	CANdevTxIdx
	)

Initialize SYNC object.

Function must be called in the communication reset section.

Parameters

SYNC	This object will be initialized.
em	Emergency object.
SDO	SDO server object.
operatingState	Pointer to variable indicating CANopen device NMT internal state.
COB_ID_SYNCMessage	From Object dictionary (index 0x1005).
communicationCyclePeriod	From Object dictionary (index 0x1006).
synchronousCounterOverflowValue	From Object dictionary (index 0x1019).
CANdevRx	CAN device for SYNC reception.
CANdevRxIdx	Index of receive buffer in the above CAN device.
CANdevTx	CAN device for SYNC transmission.
CANdevTxIdx	Index of transmit buffer in the above CAN device.

Returns

CO_ReturnError_t: CO_ERROR_NO or CO_ERROR_ILLEGAL_ARGUMENT.

CO_SYNC_initCallbackPre()

void CO_SYNC_initCallbackPre	(	CO_SYNC_t *	SYNC,
		void *	object,
		void(*)(void *object)	pFunctSignalPre
	)

Initialize SYNC callback function.

Function initializes optional callback function, which should immediately start processing of CO_SYNC_process() function. Callback is called after SYNC message is received from the CAN bus.

Parameters

SYNC	This object.
object	Pointer to object, which will be passed to pFunctSignalPre(). Can be NULL
pFunctSignalPre	Pointer to the callback function. Not called if NULL.

CO_SYNCsend()

CO_ReturnError_t CO_SYNCsend

(

CO_SYNC_t *

SYNC

)

Send SYNC message.

This function prepares and sends a SYNC object. The application should only call this if direct control of SYNC transmission is needed, otherwise use CO_SYNC_process().

Parameters

SYNC	SYNC object.

Returns

Same as CO_CANsend().

CO_SYNC_process()

CO_SYNC_status_t CO_SYNC_process	(	CO_SYNC_t *	SYNC,
		uint32_t	timeDifference_us,
		uint32_t	ObjDict_synchronousWindowLength,
		uint32_t *	timerNext_us
	)

Process SYNC communication.

Function must be called cyclically.

Parameters

	SYNC	This object.
	timeDifference_us	Time difference from previous function call in [microseconds].
	ObjDict_synchronousWindowLength	Synchronous window length variable from Object dictionary (index 0x1007).
[out]	timerNext_us	info to OS - see CO_process_SYNC_PDO().

Returns

CO_SYNC_status_t: CO_SYNC_NONE, CO_SYNC_RECEIVED or CO_SYNC_OUTSIDE_WINDOW.