Legacy Configuring Modbus and SNMP Polling of Gateways

This configuration is necessary only if you have chosen to collect readings from your gateway(s) using an application other than EMX.  If licensed for it, a gateway can serve as a source of data which you can poll from such an application using Modbus or SNMP. Configuring such a third-party application is beyond the scope of this document. References for the gateway’s implementation of those protocols may be found at:

Modbus: Modbus TCP/IP

SNMP: SNMP Data Interface

Those web pages include links to register maps (for Modbus) and MIBs (for SNMP). Both are defined for general purposes and are usable for both DC and AC (single or three-phase) monitors. Readings not relevant to DC (frequency, for example) will be null for DC monitors. For readings defined for multiple phases in an AC environment (e.g., VoltageA, VoltageB, VoltageC), use the first phase (e.g., VoltageA) for DC readings.

The readings you are most likely to need to poll, by either Modbus or SNMP, are:

VoltageA, CurrentA, PowerA, EnergyA

Modbus Node Mapping

Packet Power supports large number of monitors and other devices (known as nodes) reporting through a single gateway. You may assign a different host ID to each node, which allows support for up to 254 nodes, each using a register range of 0-199. For more than 254 nodes, registers can be renumbered with an offset to expand the address space. For example, nodes 255-508 can be mapped to registers 200-399, nodes 509-762 to registers 400-599, and so on. This concept is documented more fully on the Modbus page linked above.

SNMP Virtual IPs

By default a gateway and all the monitors reporting to it are polled at a single IP address. Many SNMP monitoring applications require each monitor (known as a node) to have a unique IP address. Packet Power gateways support the assignment of individual virtual IP addresses to the nodes which can be polled through them. This is done through the gateway console and the process is documented in the SNMP page at the link above.