# Smart Meter Gateways: Options for a BSI-Compliant Integration of Energy Management Systems
## 6 Assessment of EMS Integration Options
### Discussion of EMS Integration Option 1b  
_Option 1b_ does not utilize the HAN interface. Therefore, the only way to access measurements is via an EMP and the usage of an adequate TAF. TAF 13 for measurement visualization in the WAN could be very relevant, but has not been specified in the current version 1.0 of the BSI technical guideline [7], aside from a short description. Given the TAFs in Table 1, TAF 7 could be a suitable choice, especially since it is supported by the SMGWs of the first generation [30]. Depending on the energy management use case, other TAFs may be applicable as well. Regardless of the TAF choice, fitting parameter values need to be configured. For TAF 7, the relevant parameters are the billing period, registration period, and the time of transmission. In addition, the _Meter Profile_ needs to configure an appropriate interval for collecting meter measurements. There is no clear statement in the technical guideline for the acceptable values for each of these parameters. It only briefly states that 5 min must be supported as a billing-relevant time frame [7] (Footnote 4). _PTB-A 50.8_, on the other hand, requires registration periods of 15 min or more. To realize use cases that need more frequent measurements, the TAF needs to be configured in a way such that the data must not be used for billing purposes. Due to the degrees of freedom provided by the BSI technical guideline, it is worth noting that there may be SMGW-specific differences regarding supported parameter values. For example, the _Meter Profiles_ of some SMGW implementations may allow specifying measurement intervals of under 900 s (15 min) while others do not. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{**Measurements**} \\ \hline
**Option** & **Access via** & \multicolumn{2}{c}{**Temporal Resolution**} & \multicolumn{2}{c}{**Transport Channel**} & \multicolumn{1}{c}{**(Active) EMP**} & \multicolumn{1}{c}{**Access to CLS**} \\ \hline  & & \multicolumn{2}{c}{_TR-03109-1:_} & \(\geq\)1 s & & \\
1a & _Consumer Interface_ & & \multicolumn{2}{c}{(no TAF needed)} & & \\  & & _PTB-A 50.8_: & 15 min & & & \\ \hline
1b & EMP, TAF7 & \multicolumn{2}{c}{_TR-03109-1:_} & \(\geq\)1 s & & \\  & & _PTB-A 50.8_: & 15 min & & & \\ \hline
1c & Local EMS: & _Consumer Interface_ & Local EMS: & _TR-03109-1:_ & \(\geq\)1 s & \\  & Remote EMS: & EMP, TAF7 & Remote EMS: & _TR-03109-1:_ & 15 min & Required & Required & Indirect via local EMS \\  & & & _PTB-A 50.8_: & 15 min & & \\ \hline
2a & Local measurement collector & \multicolumn{2}{c}{As provided by meter (and collector)} & & & \\ \hline
2b & Local measurement collector & \multicolumn{2}{c}{As provided by meter (and collector)} & Required & Required & Direct \\ \hline
2c & Local measurement collector & \multicolumn{2}{c}{As provided by meter (and collector)} & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: A summary of all presented options for integrating EMSs into _Smart Metering Systems_. In the case of billing-relevant data, the temporal resolution will be 15 min for electricity and 60 min for gas. This is unsuitable for many energy management use cases that require more fine-grained measurements. When the data are not used for billing, the _PTB-A 50.8_ requirements are not applicable and the _TR-03109-1_ requirements define the theoretical constraints. The BSI technical guideline indirectly states that billing periods of 5 min or less must be supported. In this case, for _Option 1a_, the maximum resolution is likely to be determined by the meter. All options that require an EMP do require an active EMP. For _Option 1c_, it is important to note that some SMGWs separate the HAN and CLS functionally, i.e., the EMS needs to be connected to both hardware ports, HAN and CLS, to simultaneously access the _Consumer Interface_ and use the transparent data tunnel. In practice, the _SMGW Administrator_'s systems also need to support the setup of the desired configuration.