MODBUS PROTOCOL INTERFACE

MODBUS PROTOCOL INTERFACE

The established protocol for easy integration of SMA inverters

With the Modbus protocol interface, SMA makes the flexible integration of inverters possible. The benefits are obvious. Through the use of this well-known, public industry standard, other providers can integrate SMA devices into their systems without having to follow the SMA-specific inverter protocol. System data is transferred via this standardized protocol for further processing and can, as such, be flexibly integrated into any system regardless of the manufacturer. The importance for system planning: You can use SMA inverters in your preferred standard system at any time without having to take manufacturer specifics into account. Direct inverter integration into control room systems or the connection of inverters in building automation systems are both ideal applications.

Easy-to-Use

  • Easy connection of SMA inverters
  • Documented protocol standard for quick system integration

Flexible

  • Manufacturer-independent interoperability of system components through uniform protocol language

Communicative

  • Protocols uploaded directly to inverter
  • Retrieval of detailed values possible
  • High-performance Ethernet interface for the connection of data loggers or control room operated PV systems

Safety

  • Modbus recognized as an international and widespread industry standard
  • SMA, a SunSpec Alliance member, contributes to implementation of a protocol standard for PV systems

1 1 SMA Modbus: General Information

Reaction time

Question:

Why is the Modbus interface reaction time defined as only five to ten seconds in the technical documentation?

Answer:

The reaction time given is based on the worst-case reaction time analysis. This is with the intention of providing a reliable estimate for customers to minimize planning risks.
However, the reaction time of the SMA Modbus interface depends on many factors and is normally significantly less.

Number of MPP trackers

Question:

How do I read the number of MPP trackers?

Answer:

The number of MPPs cannot be read directly. However, if values relating to DC voltage (30771, 30957, 30963) are available in the case of solar irradiation, the number of MPPs can be determined using them.

Modbus crashes after a few days

Question:

Why does Modbus crash after a few days?

Answer:

This is not a crash, but instead a reaction to when more than the maximum of four TCP/Modbus connections is made.

If an attempt is made to do so, the system waits for precisely two hours. Once this time has elapsed and an existing connection has been inactive for that period, this connection is removed from our inverter bridge.

The same applies to all devices making requests to Modbus that establish a Modbus/TCP connection to the inverter but are not removed properly under fault conditions, for example.

Because we do not have any appropriate criteria for this, the inverter or the data module installed in the inverter as a TCP server cannot actively terminate the connection.

Errors with certain registers at night

Question:

Why do I receive a NaN instead of a value for some registers at night?

Answer:

SMA inverters are controlled by two processors:

a central processing unit (CPU; usually a DSP) for controlling the power electronics and measuring PV and grid variables, and a communications processor (CP; ARM or similar) for the outward-facing interfaces.

The following apply in this respect:

  • The CPU is supplied via the PV voltage and therefore runs only when solar irradiation is available.
  • The CP is supplied via both the PV system and the grid and is therefore active at all times.


If the CPU is not active, “NaN” is shown for registers with CPU data. In most cases, this can be interpreted as “0” for the power fed in, as feeding in does not take place without the CPU.

Below a particular PV voltage (much less than 80 V), it is expected that the CPU supply voltage is no longer stable and that the measured values are therefore no longer sufficiently precise. In this case, “0” is output for some devices instead of the actual measured value. This applies in particular to the measured value for PV voltage. However, this is not relevant to the grid variables, as feeding in no longer takes place below this PV voltage.

In summary, NaN can be interpreted as “0” in practically all relevant cases for the power fed in.

2 SMA Modbus: Registers

The following information is sorted by register number

30797 – grid current of line conductor

Question:

Why do registers 30797, 30799 and 30801 no longer work in the SMA Cluster Controller?

Answer:

The registers referred to represent the line conductor grid current (AC phase currents). There has been a new definition in the SMA Data2+ object model for the AC phase currents. The old objects were unsigned by the data type.

These objects are obsolete, and new signed objects have been defined accordingly. The new SMA Data2+ objects are represented in the SMA Modbus profile on new, separate register addresses. The benefit of this adjustment for SMA and customers is that an additional SunSpec requirement (signed current) can be fulfilled.

The old objects are gradually being replaced by these new objects in every CPU at SMA (e.g., in case of new developments). This means that at the same time there is an effect on the Modbus register addresses. There is currently still some overlap in terms of SMA devices, equipped with a certain communications processor (KP-COM30), that support both old and new addresses. A general switchover is planned in the future for new development projects and forthcoming product lifecycle support products.

Old SMA addresses:

30797MB_TYPE_U32/* GridMs.A.phsA */
30799MB_TYPE_U32/* GridMs.A.phsB */
30801MB_TYPE_U32/* GridMs.A.phsC */

New SMA addresses:

30977166MB_TYPE_S32/* GridMs.A.phsA */
30979167MB_TYPE_S32/* GridMs.A.phsB */
30981168MB_TYPE_S32/* GridMs.A.phsC */

30799 – grid current of line conductor

Question:

Why do registers 30797, 30799 and 30801 no longer work in the SMA Cluster Controller?

Answer:

The registers referred to represent the line conductor grid current (AC phase currents). There has been a new definition in the SMA Data2+ object model for the AC phase currents. The old objects were unsigned by the data type.

These objects are obsolete, and new signed objects have been defined accordingly. The new SMA Data2+ objects are represented in the SMA Modbus profile on new, separate register addresses. The benefit of this adjustment for SMA and customers is that an additional SunSpec requirement (signed current) can be fulfilled.

The old objects are gradually being replaced by these new objects in every CPU at SMA (e.g., in case of new developments). This means that at the same time there is an effect on the Modbus register addresses. There is currently still some overlap in terms of SMA devices, equipped with a certain communications processor (KP-COM30), that support both old and new addresses. A general switchover is planned in the future for new development projects and forthcoming product lifecycle support products.

Old SMA addresses:

30797MB_TYPE_U32/* GridMs.A.phsA */
30799MB_TYPE_U32/* GridMs.A.phsB */
30801MB_TYPE_U32/* GridMs.A.phsC */


New SMA addresses:

30977166MB_TYPE_S32/* GridMs.A.phsA */
30979167MB_TYPE_S32/* GridMs.A.phsB */
30981168MB_TYPE_S32/* GridMs.A.phsC */

30801 – grid current of line conductor

Question:

Why do registers 30797, 30799 and 30801 no longer work in the SMA Cluster Controller?

Answer:

The registers referred to represent the line conductor grid current (AC phase currents). There has been a new definition in the SMA Data2+ object model for the AC phase currents. The old objects were unsigned by the data type.

These objects are obsolete, and new signed objects have been defined accordingly. The new SMA Data2+ objects are represented in the SMA Modbus profile on new, separate register addresses. The benefit of this adjustment for SMA and customers is that an additional SunSpec requirement (signed current) can be fulfilled.

The old objects are gradually being replaced by these new objects in every CPU at SMA (e.g., in case of new developments). This means that at the same time there is an effect on the Modbus register addresses. There is currently still some overlap in terms of SMA devices, equipped with a certain communications processor (KP-COM30), that support both old and new addresses. A general switchover is planned in the future for new development projects and forthcoming product lifecycle support products.

Old SMA addresses:

30797MB_TYPE_U32/* GridMs.A.phsA */
30799MB_TYPE_U32/* GridMs.A.phsB */
30801MB_TYPE_U32/* GridMs.A.phsC */

New SMA addresses:

30977166MB_TYPE_S32/* GridMs.A.phsA */
30979167MB_TYPE_S32/* GridMs.A.phsB */
30981168MB_TYPE_S32/* GridMs.A.phsC */

40016 - Active power set point default setting

Question:

If active power limitation by the system controls is absent and the inverter no longer receives any control commands (e.g., due to an interruption in communication), does it return to a default value?
What is this default value and how long is the timeout?

Answer:

The action that the inverter is to perform in the event of an interruption in communication can be set via Modbus.
Register 41193 is used for the operating mode for absent active power limitation. The time for the timeout, during which the previously defined action is to be performed, must also be set in register 41195. If you have opted for a fallback power, the power level must be set as a % in register 41197.

40155 – MAC address

Question:

Why are multiple registers (40155/40497) available for MAC addresses?

Answer:

SMA register 40155 for the MAC address is incorrect, obsolete and marked as not to be used. Use the newer register, 40497.

40497 – MAC address

Question:

Why are multiple registers (40155/40497) available for MAC addresses?

Answer:

SMA register 40155 for the MAC address is incorrect, obsolete and marked as not to be used. Use the newer register, 40497.

3 SMA SunSpec Modbus: General Information

Cyclical system control

Question:

Which registers may be cyclically written for system control without destroying the device’s flash memory?

Answer:

Please observe the relevant safety information in the documentation (safety information section). Registers for cyclical changes are marked with the addition „Parameters for system control.“

4 SMA SunSpec Modbus: Registers

The following information is sorted by register number

40186 – model ID (ID)

Question:

Why is a value of 325 returned instead of the expected ID:101 for a single-phase inverter in the case of the SB nn00TL-21, PKG 2.60 and SB nn00TLST-21, PKG 2.60 inverters?

Answer:

This is an error in SMA mapping that no longer occurs in this way with other inverters. The aim is to eliminate this error in future versions. The value of 325 can be set as equal to 101.

40217 – DC power (DCW), in W*10

Question:

Why is the value not available for the SMA inverters?

Answer:

The DC power is not available as a cumulative value. It must be added up individually in SunSpec model 160 in consideration of the existing MPP-Trackers (see registers 40632 et seq.).

40219 – internal temperature (TmpCab), in °C

Question:

Why is the value not available for the SMA inverters?

Answer:

The internal temperature value is currently available only for certain inverters.

40224 – operating status (St)

Question:

Why is the value not available for the SMA inverters?

Answer:

Register 40224 with information on the operating status was introduced at SMA only in July 2016 for the SB n000TL-US-22 device series. It may be that it cannot be offered in all inverters for this reason.

40353 – choking (WMaxLim_Ena)

(SMA: feed-in management operating mode): activation of active power limitation setpoint

Question:

Why can I not activate the value?

Answer:

This value must be activated within the inverter’s first ten operating hours. After that, an SMA Grid Guard password is required.


Question:

Why can I not deactivate this control element by using the value “0”?

Answer:

Deactivation would not make sense for ensuring faultless operation. The inverter would ideally have to be set to default; however, SunSpec does not allow this setting. SMA therefore does not offer deactivation via SunSpec.

40358 – fixed power factor (OutPFSet_Ena)

(SMA: operating mode of static voltage stability): activation of cos φ setpoint

Question:

Why can I not activate the value?

Answer:

This value must be activated within the inverter’s first ten operating hours. After that, an SMA Grid Guard password is required.


Question:

Why can I not deactivate this control element by using the value “0”?

Answer:

Deactivation would not make sense for ensuring faultless operation. The inverter would ideally have to be set to default; however, SunSpec does not allow this setting. SMA therefore does not offer deactivation via SunSpec.

40366 – control of reactive power limitation percentage (VArPct_Ena)

(SMA: operating mode of static voltage stability): activation of reactive power setpoint

Question:

Why can I not activate the value?

Answer:

This value must be activated within the inverter’s first ten operating hours. After that, an SMA Grid Guard password is required.


Question:

Why can I not deactivate this control element by using the value “0”?

Answer:

Deactivation would not make sense for ensuring faultless operation. The inverter would ideally have to be set to default; however, SunSpec does not allow this setting. SMA therefore does not offer deactivation via SunSpec.

40632 – ID of MPP tracker (ID): 1

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40641 – DC input 1 (DCA), in A*10

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40642 – DC voltage input 1 (DCV), in V*10

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40643 – DC power input 1 (DCW), in W*10

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40652 – ID of MPP tracker (ID): 2

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40661 – DC input 2 (DCA), in A*10

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40662 – DC voltage input 2 (DCV), in V*10

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

40663 – DC power input 2 (DCW), in W*10

Question:

Why is the value not available for the STP nn000TL-10, PKG 2.65 inverters?

Answer:

The register is present in the inverter. For technical reasons with the STP nn000TL-10, this register cannot currently be documented in the device-specific list. There is no reason not to use the register.

Language

Data sheet

Modbus Protocol Interface - The established protocol for easy integration of SMA inverters MODBUS-DEN1516-V13web.pdf
  • Type: Data sheet
  • Language: English (Worldwide)
  • Number: MODBUS-DEN1516-V13
  • Version: 1.3

Certificate

Technical information

Technical Description - SMA FUEL SAVE CONTROLLER (FSC11CONT) Modbus® Interface FSC11_Modbus-TB-en-10.pdf
  • Type: Technical information
  • Language: International
  • Number: FSC11_Modbus-TB-en-10
  • Version: 1.0
Technical Information - SC-COM Modbus® Interface for SUNNY CENTRAL of the production series CP, CP-US, CP-JP and HE-20 SC-COM-MODBUS-TB-en-22.pdf
  • Type: Technical information
  • Language: English (Worldwide)
  • Number: SC-COM-MODBUS-TB-en-22
  • Version: 2.2
Technical Information - SMA CLUSTER CONTROLLER Modbus® Interface ClusterController_MODBUS-TI-en-18.pdf
  • Type: Technical information
  • Language: English (Worldwide)
  • Number: ClusterController_MODBUS-TI-en-18
  • Version: 1.8
Technical Information - Direct Marketing Interface Direktvermarktung-TI-en-10.pdf
  • Type: Technical information
  • Language: International
  • Number: Direktvermarktung-TI-en-10
  • Version: 1.0
Technical Information - SUNNY TRIPOWER 60 SunSpec® Modbus® Interface STP60-SunSpec_Modbus-TI-en-12.pdf
  • Type: Technical information
  • Language: International
  • Number: STP60-SunSpec_Modbus-TI-en-12
  • Version: 1.2
Technische Information - Modbus®-Schnittstelle // Technical Information - Modbus® Interface SMA_Modbus-de-en_V18.zip
  • Type: Technical information
  • Language: International
  • Number: SMA_Modbus-de-en_V18
  • Version: 1.8
Technische Information - SunSpec®-Modbus®-Schnittstelle // Technical Information - SunSpec® Modbus® Interface SunSpec_Modbus-de-en_V18.zip
  • Type: Technical information
  • Language: International
  • Number: SunSpec_Modbus-de-en_V18
  • Version: 1.8