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RL-ARM User's Guide (MDK v4)

RL-RTX RL-FlashFS RL-TCPnet TCP Socket Opening TCP Connection TCP Active Open TCP Passive Open Sending TCP Data Example for Sending Data Multiple TCP Connections UDP Socket Opening UDP Connection Sending UDP Data When DHCP Enabled When ARP Cache Empty Example for Sending Data IP Multicasting Multiple UDP Connections Configuring RL-TCPnet Static Configuration System Definitions Ethernet Network Interface PPP Network Interface SLIP Network Interface UDP Socket TCP Socket BSD Socket HTTP Server Telnet Server TFTP Server TFTP Client FTP Server FTP Client DNS Client SMTP Client SNMP Agent SNTP Client Error Function Runtime Configuration Library Files Using RL-TCPnet Stand Alone With RTX Kernel Event Driven Operation IP Address Assignment Ethernet Interface PPP Interface SLIP Interface Localhost Applications HTTP Server Script Language CGI Functions Ajax Support Using XML XML Example How it works SOAP Support SOAP Interface Large POST Messages Web Pages Default Page Error Pages Web on SD Card Web Update File System Interface Http Caching How it works Internal Web External Web Multi-user Authentication Using RAM File System FCARM File Converter PRINT Directive NOPRINT Directive PAGEWIDTH Directive PAGELENGTH Directive ROOT Directive Telnet Server Command Line Interface Multi-user Authentication Sending Reply Message Short Reply Long Reply Continuous Screen Update TFTP Server File System Interface TFTP Client File System Interface FTP Server File System Interface Multi-user Authentication Supported Commands FTP Client File System Interface SMTP Client SNMP Agent MIB Database MIB Interface MIB Entry MIB Table DNS Resolver Starting DNS Device Drivers Ethernet Driver Interrupt Mode Modem Driver Serial Driver Using Serial Link Cable Connection Modem Connection Windows Dial-up Add Direct Serial Link New Dial-up Connection Configure PPP Dial-up Configure SLIP Dial-up Debugging Enabling Debug Debug Level Redirecting Output Function Overview BSD Routines CGI Routines Ethernet Routines FTP Routines HTTP Routines IGMP Routines Miscellaneous Routines Modem Routines PPP Routines Serial Routines SLIP Routines SMTP Routines SNMP Routines System Functions TCP Routines Telnet Routines TFTP Routines UDP Routines RL-CAN RL-USB Example Programs Library Reference Appendix

MIB Entry

The MIB_ENTRY structure describes the MIB variable. SNMP Agent uses this description to process local MIB variables. This structure is defined in Net_Config.h as follows:

typedef struct mib_entry {        /* << SNMP-MIB Entry Info >>          */
  U8   Type;                      /* Object Type                        */
  U8   OidLen;                    /* Object ID length                   */
  U8   Oid[MIB_OIDSZ];            /* Object ID value                    */
  U8   ValSz;                     /* Size of a Variable                 */
  void *Val;                      /* Pointer to a variable              */
  void (*cb_func)(int mode);      /* Write/Read event callback function */
} MIB_ENTRY;

The components of MIB_ENTRY structure are:

  • the Type defines the MIB variable type:
  • MIB Type Description Size
    MIB_INTEGER Signed Integer 1, 2 or 4 bytes
    MIB_OCTET_STR Octet String entry max. 110 characters
    MIB_OBJECT_ID Object Identifier entry max. 17 bytes
    MIB_IP_ADDR IP Address entry 4 bytes
    MIB_COUNTER Counter entry 1, 2 or 4 bytes
    MIB_GAUGE Gauge entry 1, 2 or 4 bytes
    MIB_TIME_TICKS Time Ticks entry 4 bytes
    The Type component may be or-ed with the MIB_ATR_RO read-only attribute. A read-only variable can not be changed by the SNMP Manager.
  • the OID specifies the Object Identification Name of the variable. It is length encoded.
    - OidLen specifies the length of the Oid[] array.
    - Oid[MIB_OIDSZ] array specifies the OID name - a length encoded binary array.
  • the Val specifies the Pointer to the variable and it's Size.
    - ValSz specifies the size of Val variable.
    - *Val is a pointer to the actual variable.
  • the cb_func specifies a Callback function which is called, when the variable is accessed by SNMP Manager. The callback function is not registered, when the value of cb_func is NULL.

    Parameter mode of the callback function specifies the access mode of SNMP Manager:

    Mode Type of Access
    MIB_READ Reads a MIB variable.
    MIB_WRITE Writes to a MIB variable.
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