SNMP vs Modbus for rack PDU monitoring
10/100M Ethernet and RS485 sit on the same monitoring board and carry the same meter values. What decides the choice is what already polls the row.
- Transport
- 10/100M × 1
- Serial
- RS485 × 1
- Protocols
- SNMP · Modbus
- Alerts
- SMTP · threshold trap
- Event store
- 20,000 entries
Path comparison
Two ports, one meter
Rows that read the same on both paths are the same meter data. The rows that differ are the transport and the way a crossing is announced.
| Item | SNMP path | Modbus path |
|---|---|---|
| Physical port | 10/100M Ethernet × 1 | RS485 × 1 |
| How values arrive | The unit is polled; a trap carries the crossing | The unit is polled as registers |
| Metered values | total per feed · per outlet | total per feed · per outlet |
| Scales | 1V · 0.1A · ±1% | 1V · 0.1A · ±1% |
| Voltage window | 90V to 350V | 90V to 350V |
| Threshold alert | Trap on crossing, thresholds set per line | Crossing read from the same threshold set |
| SMTP · same board | SMTP · same board | |
| Host software | none on the unit | none on the unit |
| Local reading | OLED at the rack | OLED at the rack |
| Event store | up to 20,000 entries | up to 20,000 entries |
| Clock | RTC hold | RTC hold |
| Remote switching | per outlet or per group | per outlet or per group |
| Ambient channel | -30°C to 100°C | -30°C to 100°C |
Integration
What the platform side needs
- PollerSNMP or Modbus
- Register mapper-line sheet
- Trapsthreshold crossings
- Log readEthernet or RS485
- Host softwarenone
Mechanism
What decides the choice
The protocol is a property of the row, not of the PDU. A hall that already polls SNMP reads the unit as one more node; a line that runs Modbus to a building controller reads the same meter values as registers.
Neither path needs host software on the unit. The board answers on the port it carries, publishes the values the local OLED shows, and raises its own alert when a value crosses the threshold set for that line. Both paths report at the same scales, so the same current read over Ethernet and over the serial line comes back at 0.1A with the same ±1% plus one digit tolerance. One unit can answer on both, which is why the register map and the MIB describe a single meter rather than two.
- Ports
- Ethernet × 1 · RS485 × 1
- Values
- per feed · per outlet
- Scales
- 1V · 0.1A · ±1%
- Alert
- trap + SMTP
-
A trap carries the crossing. When a value passes the threshold set for its line, the alert goes out over the network path and by mail.
-
A register carries the same value. A Modbus master reads the meter data on RS485 at the published scales, with no gateway in between.
-
The log is shared. Up to 20,000 dated entries, with the clock held through a power loss, readable on either port.
Register view
What a poller reads on either path
One row per item a platform asks for, at the value it receives. Every figure is published for the series.
Ethernet
10/100M
One port on the monitoring board, for a poller or the web server.
Serial
RS485
One port on the same board, for a Modbus master.
Current
0.1A
Total per feed at ±1% plus one digit, on both paths.
Voltage
1V
Read across the 90V to 350V window of the unit.
Threshold alert
trap
Raised on the crossing, with mail through the same board.
Event store
20,000
Dated entries kept for the threshold window.
Clock
RTC hold
The date on a stored entry, kept through a power loss.
Local display
OLED
IP address, current, voltage, power, energy and main switch state.
Request a quote
Send the protocol your row already runs
Name the platform that polls the rack and the lines you need read. The reply carries the protocol the unit answers on and a per-line specification sheet, in English.
Reply within 12 hours on working days. No lead time and no minimum quantity figure is published on this site.
