4.8 RS485 Modbus
The NX12 uses the Modbus RTU protocol to poll for data from connected Slave
devices. Modbus I/O mappings are loaded into the NX12 using a script file. Please
contact Nortech for assistance configuring the Modbus interface.
4.9 RTU / Communication Events
GSM signal strength is reported to the iHost system. Communication failures are
date/time stamped, logged and reported to the iHost system.
The PCB temperature within the RTU is also reported to the iHost system.
4.10 Data Log Sizes
Data logs are stored in non-volatile memory and include local date/time stamps.
▪ Binary Input Log – 1024 date/time stamped entries.
▪ Counter Input Log – 1024 date/time stamped entries.
▪ Analogue Input Log – 1024 date/time stamped entries.
▪ RTU Events Log – 1024 date/time stamped entries.
▪ Counter 30-minute Data Logs – 256 date/time stamped entries.
When a log entry fills, a “buffer overrun” event is logged (to identify a loss of data)
and then the log loops back and overwrites the oldest data. Buffer overrun log
entries are themselves date/time stamped and reported to the iHost system.
4.11 Input monitoring during iHost calls
Inputs continue to be monitored during calls to the iHost system. Depending upon
the log configuration, this may result in an immediate new call to the iHost system.
4.12 Connection between the RTU and iHost
During contact with the iHost system, the RTU performs the Slave function, serving
information upon request from the iHost system, which performs the Master
function. Data is transferred, in each direction, using a secure protocol.