snmpConnect (Function)

Architecture:	NX32L
Firmware version:	1.50.00

This function will open a connection to a SNMP device.

Input:

Host : STRING

The address of the device to connect to.

Port : DINT [1..65535] (default 161)

The port of the device to connect to.

TCP : BOOL (default FALSE)

Set to TRUE if a TCP connection is required, otherwise an UDP connection is used.

The protocol uses UDP connections as default.

Version : INT (default _SNMP_VER_2C)

The SNMP version to use.

_SNMP_VER_1	SNMP version 1. Using community names for security.
_SNMP_VER_2C	SNMP version 2. Using community names for security.
_SNMP_VER_3	SNMP version 3. More advanced security (USM/TLS), including certificates.

Community : STRING (Max 63 characters)

The community string. Used in version 1 and 2c.

Security : SINT (default _SNMP_SEC_USM)

The type of security to use. Used in version 3.

_SNMP_SEC_USM	- The USM security model. (username and password)
_SNMP_SEC_TLS	- The TSM security model. (certificates)

Level : SINT (default _SNMP_SEC_ENC)

The security level used in communication (TSM security only, see overview).

_SNMP_SEC_NONE	- No authentication or encryption
_SNMP_SEC_AUTH	- Authentication and no encryption
_SNMP_SEC_ENC	- Authentication and encryption

USMUser : PTR

Pointer to a snmpUser structure. (USM security only)

EngineID : STRING (10..64 characters or empty)

The engine ID of the peer agent (TSM) or the USM users engineID when sending traps to the manager.

Certlocal : STRING

The name of the certificate to identify the local device. (TSM security only, see overview)

Certclient : STRING

The name of the certificate to identify the peer agent. (TSM security only, see overview)

Context : STRING (Max 63 characters)

The security context name to use if needed.

Output:

Handle : SYSHANDLE

The handle to the connection.

Returns: INT

1	- Success.
0	- This function is not supported.
-2	- Invalid parameter.
-3	- Too many client sessions. See limitations on overview page.
-12	- General error.

Declaration

FUNCTION snmpConnect : INT;
VAR_INPUT
   Host           : MANDATORY STRING;
   Port           : DINT := 161;
   TCP            : BOOL := FALSE;
   Version        : INT := _SNMP_VER_2C;
   Community      : STRING;
   Security       : SINT := _SNMP_SEC_USM;

Level : SINT := _SNMP_SEC_ENC;

   UsmUser        : PTR;
   EngineID       : STRING;
   Certlocal      : STRING;
   Certclient     : STRING;
   Context        : STRING;
   Handle         : ACCESS SYSHANDLE;
END_VAR;

Example:

INCLUDE rtcu.inc

VAR
   iface    : SINT := 2;
END_VAR;

PROGRAM test;
VAR
   rc       : INT;
   var_str  : STRING;
   snmplabs : SYSHANDLE;
END_VAR;
   // Open net interface.
   rc := netOpen(iface := iface);
   DebugFmt(Message := "netOpen (rc=\1)", v1 := rc);
   WHILE NOT netConnected(iface := iface) DO
      Sleep(Delay := 2000);
   END_WHILE;

   // Establish connection with client host.
   rc := snmpConnect(
                     handle    := snmplabs,
                     community := "public",
                     host      := "demo.snmplabs.com",
                     version   := _SNMP_VER_2C
                    );
   IF rc = 1 THEN
      // Read 'sysName'
      rc := snmpGetString(handle := snmplabs, oid := "1.3.6.1.2.1.1.5", v := var_str);
      IF rc = 1 THEN
         DebugFmt(message := "snmpGetString (rc=\1): returned : '" + var_str + "'", v1 := rc);
      ELSE
         DebugFmt(message := "snmpGetString error. (rc=\1)", v1 := rc);
      END_IF;
   ELSE
      DebugFmt(message := "snmpConnect failed (rc=\1)", v1 := rc);
   END_IF;
   ...
BEGIN
   ...
END;
END_PROGRAM;