This page describes how to fix a bug in the dll of !EnergyPlus 7.1.0, build12 for Windows that may occur when exchanging a large amount of data in each time step. The error message that !EnergyPlus writes to its {{{.err}}} file is

{{{
 ExternalInterface starts first data exchange.
 Error: No digits were found in getDoubleCheckError.
 Further characters after number:
 Sending EXIT_FAILURE = : 1
 **FATAL:Error in ExternalInterface: Check EnergyPlus *.err file.
}}}
To fix the bug, proceed as follows:

= Windows =
 1. Install the BCVTB version 1.1.0.
 1. Download the bcvtb.dll for your architecture and copy it to the !EnergyPlus directory, such as {{{C:\Program Files\EnergyPlus-7-1-0}}}. This will replace the existing file with the same name.
  1. Click on [[attachment:bcvtb_win32.zip]] to download the bcvtb.dll for Windows 32 bit.
  1. Click on [[attachment:bcvtb_win64.zip]] to download the bcvtb.dll for Windows 64 bit.