To achieve Class A to IEC 61000-4-30:2008 synchronisation of the Real Time Clock (RTC) is required. M355 allows RTC synchronisation using modulated or demodulated IRIGB, 1PPS, GPS modem or SNTP (if Ethernet available). If clock synchronisation is not implemented the M355 operates as a Class S instrument.
The M355 can be defined with serial (RS232/RS485), USB or Ethernet communications ports using Modbus RTU/TCP and DNP3 (level 1) protocols. Also the M355 has a front mounted memory card slot (MMC or SD) for extracting data stored in the meter for later analysis, so connection to a communications network is not required to retrieve data.
The M355 has 4 input/output modules, 2 dual channel modules which can be factory fitted with a wide range of options, selected from analogue, alarm, pulse or watchdog outputs or analogue, temperature (PT100) or digital inputs. And 2x8 channel factory fitted digital input or output (relay) modules with status indicators on the front panel.
The M355 requires the QDSP2 software, to define and store settings, and to configure, download and analyse trend, alarm and power quality data.