examples: Update NI-DCPower readme to describe the .env simulation process (#491)

* Update readme for nidcpower and replace .env sample files to examples directory.

Author: Avinash2Suresh

.env.sample examples/.env.sample.env.sample renamed to examples/.env.sample

@@ -2,8 +2,8 @@
 #
 # To use it:
 # - Copy this file to your service's directory or one of its parent directories
-#   (such as the root of your Git repository or `C:\ProgramData\National
-#   Instruments\MeasurementLink\Services`).
+#   (such as the root of your Git repository or `C:\ProgramData\National 
+#   Instruments\MeasurementLink\Services` for statically registered measurement services).
 # - Rename it to `.env`.
 # - Uncomment and edit the options you want to change.
 # - Restart any affected services.

.env.simulation examples/.env.simulation.env.simulation renamed to examples/.env.simulation

@@ -4,8 +4,8 @@
 #
 # To use it:
 # - Copy this file to your service's directory or one of its parent directories
-#   (such as the root of your Git repository or `C:\ProgramData\National
-#   Instruments\MeasurementLink\Services`).
+#   (such as the root of your Git repository or `C:\ProgramData\National 
+#   Instruments\MeasurementLink\Services` for statically registered measurement services).
 # - Rename it to `.env`.
 # - Uncomment and edit the options you want to change.
 # - Restart any affected services.

examples/README.md

@@ -51,6 +51,10 @@ The example measurements are *Poetry-based* projects. Follow the steps below to
     ```
     - If you get a "command not found" error during `poetry install`, make sure that you added the Poetry path to the system path. Refer to [https://python-poetry.org/docs/#installing-with-the-official-installer/Add-poetry-to-your-path](https://python-poetry.org/docs/#installing-with-the-official-installer:~:text=Add%20Poetry%20to%20your%20PATH)
 
+### Creating Simulated Devices for Example Measurements
+
+- To enable simulation for all the modular instrument and VISA examples, copy `.env.simulation` to `.env` in the `examples` directory.
+
 ### Executing the Example Measurements
 
 1. Start the discovery service if not already started.

examples/nidcpower_source_dc_voltage/README.md

@@ -31,8 +31,15 @@ This is a MeasurementLink example that sources and measures a DC voltage with an
 
 This example requires an NI SMU that is supported by NI-DCPower (e.g. PXIe-4141).
 
-By default, this example uses a simulated instrument. To use a physical instrument, edit
-`_constants.py` to specify `USE_SIMULATION = False`.
+By default, this example uses a physical instrument or a simulated device created in NI MAX. To automatically create a simulated device when running the measurement or TestStand sequence, follow the steps below:
+- Create a `.env` file in the measurement service's directory or one of its parent directories (such as the root of your Git repository or `C:\ProgramData\National Instruments\MeasurementLink\Services` for statically registered measurement services).
+- Add the following options to the `.env` file to enable simulation via the driver's option string:
+
+  ```
+  MEASUREMENTLINK_NIDCPOWER_SIMULATE=1 
+  MEASUREMENTLINK_NIDCPOWER_BOARD_TYPE=PXIe
+  MEASUREMENTLINK_NIDCPOWER_MODEL=4141
+  ```
 
 > **Note**
 > The multi-site pin map, `NIDCPowerSourceDCVoltageMultiSite.pinmap`, requires an