• Do not run the Rosemount 702 Transmitter for long periods (more than
two weeks) with a nVent fuel sensor in the leak state as this will more
rapidly deplete the power module.
6.9.3 Liquid hydrocarbon detection interface, for Modbus
®
mapping
Table 6-6 describes use of the Rosemount 702 Transmitter for hydrocarbon
detection in other communication's protocols such as Modbus or OPC. It is
imperative that both PV and SV be mapped to the host system so as to make
a good interpretation of the condition and status of the leak detector.
Table 6-6: Liquid Hydrocarbon Detection Interface, for Modbus Mapping
PV SV Description/
interpretation
1.0 1.0 Normal condition, no leak
detected, sensor status
good
0.0 1.0 or 0.0 Leak detected, sensor
status good
1.0 0.0 Sensor Not Connected,
Assume Leak, take
appropriate action
NOTICE
It is imperative that both PV and SV be mapped to the host system so the
diagnostic information on the sensor status is captured.
In addition, system considerations must be observed to ensure that the
device is still connected to the wireless network and reporting values. On an
Emerson Wireless Gateway, this can be done by referring to the parameter:
PV_HEALTHY. PV_HEALTHY has a “True” state when the device is on the
network and its updates are current, not late or stale, and the device is
functioning properly. A “False” state of PV_HEALTHY means the device is
either off the network, the data updates are not current, or that there is a
malfunction of the device (such as an electronics failure). In the case of a
“False” state of PV_HEALTHY, it is recommended to assume the device is not
connected to the network and take appropriate action.
Mapping the PV, SV, and PV_HEALTHY variables and parameter
Below is a Gateway screen where the PV, SV, and PV_HEALTHY variables and
parameter can be mapped.
April 2021 Quick Start Guide
Quick Start Guide 37
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