EtherCAT主站SOEM函数详解----SDO读写函数

ethercatcoe.h头文件
SDO读写函数
- SDO读取函数
- SDO写函数

本篇ethercatcoe文件相关的函数，COE的全称是CanOpen over EtherCAT, 采用CanOpen的相关协议开发了EtherCAT的运用层，核心是对象字典，想了解PDO相关知识，可以读CanOpen通信----PDO与SDO。对于报文结构体相关知识，可以参照EtherCAT数据帧及SOEM报文数据结构介绍,对下文的理解有一定帮组。

ethercatcoe.h头文件

为了比较全面的了解COE, 本文将先给出ethercatcoe.h的头文件，如下所示，其中核心的是读写函数。

/*
 * Licensed under the GNU General Public License version 2 with exceptions. See
 * LICENSE file in the project root for full license information
 */
/** \file
 * \brief
 * Headerfile for ethercatcoe.c
 */
#ifndef _ethercatcoe_
#define _ethercatcoe_
#ifdef __cplusplus
extern "C"
{
    
    
#endif
/** max entries in Object Description list */
#define EC_MAXODLIST   1024
/** max entries in Object Entry list */
#define EC_MAXOELIST   256
/* Storage for object description list */
typedef struct
{
    
    
   /** slave number */
   uint16  Slave;
   /** number of entries in list */
   uint16  Entries;
   /** array of indexes */
   uint16  Index[EC_MAXODLIST];
   /** array of datatypes, see EtherCAT specification */
   uint16  DataType[EC_MAXODLIST];
   /** array of object codes, see EtherCAT specification */
   uint8   ObjectCode[EC_MAXODLIST];
   /** number of subindexes for each index */
   uint8   MaxSub[EC_MAXODLIST];
   /** textual description of each index */
   char    Name[EC_MAXODLIST][EC_MAXNAME+1];
} ec_ODlistt;
/* storage for object list entry information */
typedef struct
{
    
    
   /** number of entries in list */
   uint16 Entries;
   /** array of value infos, see EtherCAT specification */
   uint8  ValueInfo[EC_MAXOELIST];
   /** array of value infos, see EtherCAT specification */
   uint16 DataType[EC_MAXOELIST];
   /** array of bit lengths, see EtherCAT specification */
   uint16 BitLength[EC_MAXOELIST];
   /** array of object access bits, see EtherCAT specification */
   uint16 ObjAccess[EC_MAXOELIST];
   /** textual description of each index */
   char   Name[EC_MAXOELIST][EC_MAXNAME+1];
} ec_OElistt;
#ifdef EC_VER1
void ec_SDOerror(uint16 Slave, uint16 Index, uint8 SubIdx, int32 AbortCode);
int ec_SDOread(uint16 slave, uint16 index, uint8 subindex,
                      boolean CA, int *psize, void *p, int timeout);
int ec_SDOwrite(uint16 Slave, uint16 Index, uint8 SubIndex,
    boolean CA, int psize, void *p, int Timeout);
int ec_RxPDO(uint16 Slave, uint16 RxPDOnumber , int psize, void *p);
int ec_TxPDO(uint16 slave, uint16 TxPDOnumber , int *psize, void *p, int timeout);
int ec_readPDOmap(uint16 Slave, int *Osize, int *Isize);
int ec_readPDOmapCA(uint16 Slave, int Thread_n, int *Osize, int *Isize);
int ec_readODlist(uint16 Slave, ec_ODlistt *pODlist);
int ec_readODdescription(uint16 Item, ec_ODlistt *pODlist);
int ec_readOEsingle(uint16 Item, uint8 SubI, ec_ODlistt *pODlist, ec_OElistt *pOElist);
int ec_readOE(uint16 Item, ec_ODlistt *pODlist, ec_OElistt *pOElist);
#endif
void ecx_SDOerror(ecx_contextt *context, uint16 Slave, uint16 Index, uint8 SubIdx, int32 AbortCode);
int ecx_SDOread(ecx_contextt *context, uint16 slave, uint16 index, uint8 subindex,
                      boolean CA, int *psize, void *p, int timeout);
int ecx_SDOwrite(ecx_contextt *context, uint16 Slave, uint16 Index, uint8 SubIndex,
    boolean CA, int psize, void *p, int Timeout);
int ecx_RxPDO(ecx_contextt *context, uint16 Slave, uint16 RxPDOnumber , int psize, void *p);
int ecx_TxPDO(ecx_contextt *context, uint16 slave, uint16 TxPDOnumber , int *psize, void *p, int timeout);
int ecx_readPDOmap(ecx_contextt *context, uint16 Slave, int *Osize, int *Isize);
int ecx_readPDOmapCA(ecx_contextt *context, uint16 Slave, int Thread_n, int *Osize, int *Isize);
int ecx_readODlist(ecx_contextt *context, uint16 Slave, ec_ODlistt *pODlist);
int ecx_readODdescription(ecx_contextt *context, uint16 Item, ec_ODlistt *pODlist);
int ecx_readOEsingle(ecx_contextt *context, uint16 Item, uint8 SubI, ec_ODlistt *pODlist, ec_OElistt *pOElist);
int ecx_readOE(ecx_contextt *context, uint16 Item, ec_ODlistt *pODlist, ec_OElistt *pOElist);
#ifdef __cplusplus
}
#endif
#endif

SDO读写函数

SDO服务数据，也称为邮箱数据，通常用在驱动器配置阶段，其数据传输是非周期性的。

SDO读取函数

int ecx_SDOread(ecx_contextt *context, uint16 slave, uint16 index, uint8 subindex,
                      boolean CA, int *psize, void *p, int timeout);
/** CoE SDO read, blocking. Single subindex or Complete Access.
 *
 * Only a "normal" upload request is issued. If the requested parameter is <= 4bytes
 * then a "expedited" response is returned, otherwise a "normal" response. If a "normal"
 * response is larger than the mailbox size then the response is segmented. The function
 * will combine all segments and copy them to the parameter buffer.
 *
 * @param[in]  context    = context struct
 * @param[in]  slave      = Slave number
 * @param[in]  index      = Index to read
 * @param[in]  subindex   = Subindex to read, must be 0 or 1 if CA is used.
 * @param[in]  CA         = FALSE = single subindex. TRUE = Complete Access, all subindexes read.
 * @param[in,out] psize   = Size in bytes of parameter buffer, returns bytes read from SDO.
 * @param[out] p          = Pointer to parameter buffer
 * @param[in]  timeout    = Timeout in us, standard is EC_TIMEOUTRXM
 * @return Workcounter from last slave response
 */

参数解释：

ecx_contextt *context：报文结构体指针，所有信息都是通过报文传递的，报文中包含了一系列配置信息；
uint16 slave ：从站编号，有顺序寻址、逻辑寻址等，采用顺序寻址在驱动器配置过程自动扫描分配，与连接顺序有关；
uint16 index：对象字典索引，CanOpen相关协议
uint8 subindex：对象字典子索引，CanOpen相关协议
boolean CA：完全访问（Complete Access），会访问所有子索引，一般填写False,仅访问给定子索引。
int *psize：读取参数字节数
void *p：读取参数指针，通过该指针可获取想要的信息
int timeout：读取最大超时，单位us（微秒），一般给EC_TIMEOUTRXM，其值为700000
@return Workcounter：返回计数wck,用于对比是否正确处理报文。

SDO写函数

int ecx_SDOwrite(ecx_contextt *context, uint16 Slave, uint16 Index, uint8 SubIndex,
    boolean CA, int psize, void *p, int Timeout);
/** CoE SDO write, blocking. Single subindex or Complete Access.
 *
 * A "normal" download request is issued, unless we have
 * small data, then a "expedited" transfer is used. If the parameter is larger than
 * the mailbox size then the download is segmented. The function will split the
 * parameter data in segments and send them to the slave one by one.
 *
 * @param[in]  context    = context struct
 * @param[in]  Slave      = Slave number
 * @param[in]  Index      = Index to write
 * @param[in]  SubIndex   = Subindex to write, must be 0 or 1 if CA is used.
 * @param[in]  CA         = FALSE = single subindex. TRUE = Complete Access, all subindexes written.
 * @param[in]  psize      = Size in bytes of parameter buffer.
 * @param[out] p          = Pointer to parameter buffer
 * @param[in]  Timeout    = Timeout in us, standard is EC_TIMEOUTRXM
 * @return Workcounter from last slave response