SYNC

CANopen Synchronisation protocol. More...

Collaboration diagram for 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_RX_TX = 1 , CO_SYNC_PASSED_WINDOW = 2 }
	Return value for CO_SYNC_process. More...

Functions
CO_ReturnError_t	CO_SYNC_init (CO_SYNC_t *SYNC, CO_EM_t *em, OD_entry_t *OD_1005_cobIdSync, OD_entry_t *OD_1006_commCyclePeriod, OD_entry_t *OD_1007_syncWindowLen, OD_entry_t *OD_1019_syncCounterOvf, CO_CANmodule_t *CANdevRx, uint16_t CANdevRxIdx, CO_CANmodule_t *CANdevTx, uint16_t CANdevTxIdx, uint32_t *errInfo)
	Initialize SYNC object.
void	CO_SYNC_initCallbackPre (CO_SYNC_t *SYNC, void *object, void(*pFunctSignalPre)(void *object))
	Initialize SYNC callback function.
static CO_ReturnError_t	CO_SYNCsend (CO_SYNC_t *SYNC)
	Send SYNC message.
CO_SYNC_status_t	CO_SYNC_process (CO_SYNC_t *SYNC, bool_t NMTisPreOrOperational, uint32_t timeDifference_us, uint32_t *timerNext_us)
	Process SYNC communication.

Detailed Description

CANopen Synchronisation protocol.

For CAN identifier see Default CANopen identifiers

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	No SYNC event in last cycle.
CO_SYNC_RX_TX	SYNC message was received or transmitted in last cycle.
CO_SYNC_PASSED_WINDOW	Time has just passed SYNC window (OD_1007) in last cycle.

Function Documentation

CO_SYNC_init()

CO_ReturnError_t CO_SYNC_init	(	CO_SYNC_t *	SYNC,
		CO_EM_t *	em,
		OD_entry_t *	OD_1005_cobIdSync,
		OD_entry_t *	OD_1006_commCyclePeriod,
		OD_entry_t *	OD_1007_syncWindowLen,
		OD_entry_t *	OD_1019_syncCounterOvf,
		CO_CANmodule_t *	CANdevRx,
		uint16_t	CANdevRxIdx,
		CO_CANmodule_t *	CANdevTx,
		uint16_t	CANdevTxIdx,
		uint32_t *	errInfo )

Initialize SYNC object.

Function must be called in the communication reset section.

Parameters

	SYNC	This object will be initialized.
	em	Emergency object.
	OD_1005_cobIdSync	OD entry for 0x1005 - "COB-ID SYNC message", entry is required.
	OD_1006_commCyclePeriod	OD entry for 0x1006 - "Communication cycle period", entry is required if device is sync producer.
	OD_1007_syncWindowLen	OD entry for 0x1007 - "Synchronous window length", entry is optional, may be NULL.
	OD_1019_syncCounterOvf	OD entry for 0x1019 - "Synchronous counter overflow value", entry is optional, may be NULL.
	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.
[out]	errInfo	Additional information in case of error, may be NULL.

Returns

CO_ReturnError_t CO_ERROR_NO on success.

CO_SYNC_initCallbackPre()

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

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().
pFunctSignalPre	Pointer to the callback function. Not called if NULL.

CO_SYNCsend()

static CO_ReturnError_t CO_SYNCsend ( CO_SYNC_t * SYNC )

inlinestatic

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,
		bool_t	NMTisPreOrOperational,
		uint32_t	timeDifference_us,
		uint32_t *	timerNext_us )

Process SYNC communication.

Function must be called cyclically.

Parameters

	SYNC	This object.
	NMTisPreOrOperational	True if this node is NMT_PRE_OPERATIONAL or NMT_OPERATIONAL state.
	timeDifference_us	Time difference from previous function call in [microseconds].
[out]	timerNext_us	info to OS - see CO_process().

Returns

CO_SYNC_status_t