TABLE OF CONTENTS
E 21
SNMP
1) General information's
SNMP (Simple Network Management Protocol) is the most widely used protocol for managing network devices. It is
based on UDP protocol and provides the control code transmission and reception of response between different network
devices. It is based on two main elements: a manager (which generates commands and receives the response mes-
sages) and agents (that answer to commands and can generate messages).
To communicate with the different agents, the manager use a database (MIB) dedicated to this agent. This MIB forms a
tree structure that includes various accessible parameters of the agent. To access a data item, the manager must know
the location of this item in the MIB tree. This location (OID) is represented by a sequence of numbers separated by dots.
The manager sends request to agents by the UDP port 161. This requests therefore contain the OID (the path) of the
parameter and the type of action to perform (read or write).
But an agent can also sends message (traps) on UDP port 162. This traps are alert messages issued by agent to the
snmp manager to report abnormal events.
2) Use
The CPL165 is a SNMP v1 agent. The supervisor can read all the measures made by the device:
- Measures for phase 1 (voltage, currents, phi cosines, powers and energies),
- Measures for phase 2 (voltage, currents, phi cosines, powers and energies),
- Measures for phase 3 (voltage, currents, phi cosines, powers and energies),
- Measures total (powers and energies per channel).
The format for voltage is 16bits, V x 10
The format for current is 16bits, A x 100
The format for power factor is 16bits value x 100
The format for power is 32bits, W x 100
The format for energy is 32bits, kWh x 100
The MIB file is incorporated into the device. It can be downloaded by going on his web page, in the SNMP tab.
