C API getMeterHandle() can't return handle for first meter

Issue overview

There's a small bug in the C API for getMeterHandle().
The code here expects EnergyPlus::GetMeterIndex() to return 0 if the meter is not found. However 0 IS a valid result. EnergyPlus::GetMeterIndex() returns -1 when the meter is not found.

EnergyPlus/src/EnergyPlus/api/datatransfer.cc

Lines 385 to 395 in e84d72a

    
           int getMeterHandle(EnergyPlusState state, const char *meterName) 
        
           { 
        
               auto *thisState = static_cast<EnergyPlus::EnergyPlusData *>(state); 
        
               std::string const meterNameUC = EnergyPlus::Util::makeUPPER(meterName); 
        
               const int i = EnergyPlus::GetMeterIndex(*thisState, meterNameUC); 
        
               if (i == 0) { 
        
                   // inside E+, zero is meaningful, but through the API, I want to use negative one as a signal of a bad lookup 
        
                   return -1; 
        
               } 
        
               return i; 
        
           }

There are some stale docstrings but you can see the -1 on the end of line 4112

EnergyPlus/src/EnergyPlus/OutputProcessor.cc

Lines 4097 to 4113 in e84d72a

    
           int GetMeterIndex(EnergyPlusData const &state, std::string const &name) 
        
           { 
        
               // FUNCTION INFORMATION: 
        
               //       AUTHOR         Linda K. Lawrie 
        
               //       DATE WRITTEN   August 2002 
        
               // PURPOSE OF THIS FUNCTION: 
        
               // This function returns a index to the meter "number" (aka assigned report number) 
        
               // for the meter name.  If none active for this run, a zero is returned.  This is used later to 
        
               // obtain a meter "value". 
        
               auto const &op = state.dataOutputProcessor; 
        
               auto found = op->meterMap.find(name); 
        
               return (found != op->meterMap.end()) ? found->second : -1; 
        
           } // GetMeterIndex()

Because of this, I can't get the Electricity:Facility meter (which tends to be the first) for my simulation.

The fix should be as simple as removing the if (i == 0) block in datatransfer.cc.

Operating System (Multiple choices)

Any, Ubuntu

Operating System Version

24.04

Version of EnergyPlus

26.1.0

Unmethours link or helpdesk ticket number

N/A

Defect file

Here's a minimal example to reproduce the problem. The python wrapper just passes the values through, so hit's the same problem.

import sys

ENERGYPLUS_INSTALL_DIR = "/root/energyplus"
sys.path.insert(0, ENERGYPLUS_INSTALL_DIR)
from pyenergyplus.api import EnergyPlusAPI

api = EnergyPlusAPI()

state = api.state_manager.new_state()


def handle_step(state):
    facility_handle = api.exchange.get_meter_handle(state, "Electricity:Facility")  # <- This SHOULD return 0, but it returns -1
    building_handle = api.exchange.get_meter_handle(state, "Electricity:Building")
    facility_value = api.exchange.get_meter_value(state, 0)  # <- Passing 0 explicitly returns the correct value
    building_value = api.exchange.get_meter_value(state, building_handle)
    print({
        'facility_handle': facility_handle,
        'building_handle': building_handle,
        'facility_value': facility_value,
        'building_value': building_value,
    })


api.runtime.callback_after_predictor_after_hvac_managers(state, handle_step)

api.runtime.run_energyplus(state, [
    '--output-directory', 'output',
    '--weather', ENERGYPLUS_INSTALL_DIR + '/WeatherData/USA_IL_Chicago-OHare.Intl.AP.725300_TMY3.epw',
    ENERGYPLUS_INSTALL_DIR + '/ExampleFiles/5ZoneAirCooled.idf',
])

Navigation Menu

Repository navigation

C API getMeterHandle() can't return handle for first meter #11522

Issue overview

Operating System (Multiple choices)

Operating System Version

Version of EnergyPlus

Unmethours link or helpdesk ticket number

Defect file

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

	int getMeterHandle(EnergyPlusState state, const char *meterName)
	{
	auto thisState = static_cast<EnergyPlus::EnergyPlusData >(state);
	std::string const meterNameUC = EnergyPlus::Util::makeUPPER(meterName);
	const int i = EnergyPlus::GetMeterIndex(*thisState, meterNameUC);
	if (i == 0) {
	// inside E+, zero is meaningful, but through the API, I want to use negative one as a signal of a bad lookup
	return -1;
	}
	return i;
	}

	int GetMeterIndex(EnergyPlusData const &state, std::string const &name)
	{

	// FUNCTION INFORMATION:
	// AUTHOR Linda K. Lawrie
	// DATE WRITTEN August 2002

	// PURPOSE OF THIS FUNCTION:
	// This function returns a index to the meter "number" (aka assigned report number)
	// for the meter name. If none active for this run, a zero is returned. This is used later to
	// obtain a meter "value".

	auto const &op = state.dataOutputProcessor;

	auto found = op->meterMap.find(name);
	return (found != op->meterMap.end()) ? found->second : -1;
	} // GetMeterIndex()

C API getMeterHandle() can't return handle for first meter #11522

Description

Issue overview

Operating System (Multiple choices)

Operating System Version

Version of EnergyPlus

Unmethours link or helpdesk ticket number

Defect file

Activity

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions