# ESS that can talk with OpenEMS using Modbus TCP

**URL:** <https://community.openems.io/t/ess-that-can-talk-with-openems-using-modbus-tcp/1029>\
**Category:** Uncategorized\
**Created:** [July 21, 2022, 9:08am UTC](https://community.openems.io/t/ess-that-can-talk-with-openems-using-modbus-tcp/1029 "2022-07-21T09:08:51Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![klinki](https://community.openems.io/letter_avatar_proxy/v4/letter/k/858c86/32.png) [@klinki](https://community.openems.io/u/klinki)\
**Post date:** [March 5, 2023, 5:18pm UTC](https://community.openems.io/t/ess-that-can-talk-with-openems-using-modbus-tcp/1029/3 "2023-03-05T17:18:11Z")

</div>

Hi Stefan,

As I was able to get my SolardEdge Battery system working I’ve tried to implement the write registers for getting control over charge/discharge power.  
I´ve implemented SymmetricEss and MangedSymmetricEss natures. But I´m stuck getting the `this.ess.setActivePowerEquals(this.config.power());` method working.

Is it right to feed just the registers

```auto
		protocol.addTask(//
		new FC16WriteRegistersTask(0xE00E, //
				m(ManagedSymmetricEss.ChannelId.SET_ACTIVE_POWER_EQUALS, new FloatDoublewordElement(0xE00E).wordOrder(WordOrder.LSWMSW),
						ElementToChannelConverter.SCALE_FACTOR_2), //
				m(ManagedSymmetricEss.ChannelId.SET_REACTIVE_POWER_EQUALS, new FloatDoublewordElement(0xE010).wordOrder(WordOrder.LSWMSW),
						ElementToChannelConverter.SCALE_FACTOR_2))); //

```

The Log

```auto
2023-03-05T18:10:15,216 [_cycle] INFO [enems.edge.ess.power.api.Power] [SetActivePowerEquals] reducing requested [1000 W] to maximum power [0 W] for [ess0P]
2023-03-05T18:10:15,216 [_cycle] WARN [r.solver.CalculatePowerExtrema] Unable to MINIMIZE [ess0] phase [ALL] pwr [ACTIVE]. Setting it to zero.
2023-03-05T18:10:15,217 [_cycle] WARN [ms.edge.core.cycle.CycleWorker] [_cycle] Error in Controller [ctrlFixActivePower0]: No Feasible Solution [Channel [SetActivePowerEquals]+ess0P EQUALS 0]
2023-03-05T18:10:15,218 [_cycle] WARN [ems.edge.ess.core.power.Solver] Power-Solver: Unable to solve under constraints!
2023-03-05T18:10:16,250 [modbusWR] INFO [bstractOpenemsSunSpecComponent] [meter0] Ignoring SunSpec-Model [713] starting at [41264]

```

I`ve also took a look on the fenecon commercial. But I still don´t unterstanbd relation between the single natures.  
The only thing in the first step is to control the charge power of the system to get a time of use tariff working in the second step.

Have you got any hints for me?

regards  
klinki

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