# Industrial IoT Monitoring: Technologies and Architecture Proposal
## 5 Proof-of-Concept
### Results  
In order to show that the proposed architecture can be implemented in industrial scenarios with efficiency and low impact on resource consumption, some experiments were conducted, whose results are described in this sub-section. Figure 3: On the left, (**a**) the application architecture and the sensor node monitoring agent acquiring the state information. On the right, (**b**) the request of the WirelessHART publish service. The performed tests can be divided in two groups: tests that measure the impact on the sensor node resources, and tests that measure the network operation overhead introduced by the sensor node monitoring agent. It should be noted that, as presented in Section 2, the industrial standards addressed in this paper already share network metrics to perform routing and other network related operations and, thus, these metrics do not add extra overhead to the network operation. Hence, the only network overhead is the one caused by sensor node monitoring agents. For the first group of tests, the used hardware and software were, respectively, the Texas Instrument MSP-FET (with EnergyTrace technology support) and the Code Composer Studio (CCS, version 7, Texas Instruments) connected directly to the launchpad debug pins and bypassing the board debugger. Each test was performed during 30 s and repeated 10 times. In the second group of tests, the gateway monitoring agent was used to collect the impact of the traffic generated by the sensor node monitoring agent on the network, by collecting device health reports. In these tests, we collected health reports over a period of 10 h. The results presented in Figure 4 show (a) the impact of the hardware techniques on the sensor node battery lifetime; (b) the overall impact of the sensor node monitoring agent on the sensor node lifetime; (c,d) the impact of the sensor node monitoring agent on the microcontroller processing and memory, respectively; and (e) the overhead caused by the transport of the sensor node monitoring data over the network. In order to measure the impact of the hardware monitoring metrics on sensor node resources, a simplified version of the industrial application was developed with the objective of guaranteeing the independence of each added metric. In this test, the energy expenditure was measured by the MSP-FET. Additionally, the radio was disconnected in order to allow the easy detection of the comparatively small increase of energy expenditure caused by each hardware metric. As shown in Figure 4a, the energy spent by the MSP430 in LPM3 without any hardware metric enabled is around 4.1 \(\upmu\)A. Enabling the processing metric does not increase the energy spent by the microcontroller. In this LPM, the MCLK and the SMCLK are turned off and, consequently, the processing metric interrupt will not occur when the microcontroller is in LPM. On the other hand, the energy counter increases the microcontroller energy expenditure in LPM because, even in this LPM mode, the system consumes energy and, as a result, the interrupt associated with the energy counter mechanism will be executed (this interrupt is tied with an hardware counter that is sourced  
Figure 4: Obtained results. by an external clock). In this mode, when enabled, the microcontroller counter consumes 12.1 \(\upmu\)A (\(\sigma\) = 0.00 \(\upmu\)A). Lastly, the time counter, sourced by the ACLK consumes around 33.2 \(\upmu\)A (\(\sigma\) = 0.05 \(\upmu\)A). Contrary to the significant increase in energy consumption in LPM associated with each metric, the energy spent by the complete solution in active mode with the radio on (acquisition plus transport of the monitoring data) only corresponds to a 3.5% increase (Figure 4b) in relation to a non-monitoring situation. Using two AA NiMh batteries (1.2 v, 1900 mA), the lifetime of the sensor node is 658 days (\(\sigma\) = 6 days) without monitoring and 635 days (\(\sigma\) = 12 days) with the sensor node monitoring agent enabled.