The PLAXIS software provides an HTTP-based API (REST HTTP API), for which a special Python wrapper was developed for an easy-to-use scripting API. Both PLAXIS Input and PLAXIS Output support this usage of a Remote Scripting server.

The information in this article applies to both 2D and 3D 2017 versions and later, as well as to 3D 2016 version. For older versions, please see the attachment at the end of this article.

Prerequisites

In order to use this:

• a Bentley Geotechnical SELECT Entitlement [GSE] (former PLAXIS-VIP) license is required
• An editor for writing Python scripts. This article assumes that the SciTE editor will be used that comes with the PLAXIS installation. You can find it under Expert > Python > Editor...
  
• At least a very rudimentary knowledge of the Python language is recommended. The Plaxis documentation makes no attempt to teach it. Good resources for this purpose are e.g.:
  • Dive into Python 3: http://diveintopython3.problemsolving.io/
  • After hours programming: http://www.afterhoursprogramming.com/tutorial/Python/Overview/
  • Think Python: How to Think Like a Computer Scientist: http://greenteapress.com/thinkpython/html/index.html
• The firewall should not block the PLAXIS application from accessing the internet, nor must it block other applications (in particular the python.exe and pythonw.exe executable) from communicating with the remote scripting server inside the PLAXIS application.

Activate scripting server

In order to start using this Remote Scripting/REST HTTP API, the remote scripting server inside PLAXIS needs to be activated.
This can be done by opening the menu item Expert > Configure remote scripting server.
The corresponding window will pop up, see Figure 1 for PLAXIS 2D and PLAXIS 3D:

Figure 1. Configure remote scripting server window in PLAXIS 2D and PLAXIS 3D

For the Remote Scripting server to run, you would need:

1. A valid Bentley Geotechnical SELECT Entitlement [GSE] (former PLAXIS-VIP) license
2. A password to ensure a secure connection between the server and the remote scripting interface. PLAXIS Input generates by default a password.
   Be aware that an empty text box disables the encryption.
3. The local connection port needs to be configured and the server activated

Figure 2. Run the remote scripting server requirements:
1) a valid license, 2) a password and 3) a local connection port

Boilerplate code

In order to start your first Python script, you can start SciTE from PLAXIS. First, we must import the PLAXIS scripting library. Then, you must make sure that your Python script can communicate with the PLAXIS application (assuming the scripting server port was set to 10000, see above):

from plxscripting.easy import *
s_i, g_i = new_server('localhost', 10000, password='yourpassword')

In this, we need to set the correct localhost port using the same number as set in the Configure remote scripting server window as well as the password field required.

Now we have two new variables:

• s_i: this is bound to an object representing the PLAXIS Input Application (the Remote scripting server).
• g_i: this variable is bound to the global object of the current open Plaxis model in Input. This should be used when you want to make changes to the model (e.g., adding a borehole or a point, generating the mesh and starting the calculation).

For PLAXIS Output, the recommended variable names are:

• s_o: this is bound to an object representing the PLAXIS Output Application (the Remote scripting server).
• g_o: this variable is bound to the global object of the current open Plaxis model in Output. This should be used when you want to access Output objects (e.g., retrieve results, set up a plot, switch to a specific phase).

PLAXIS Input and PLAXIS Output

Note, if you want to use both PLAXIS Input and PLAXIS Output in your Python script, you will need to set up the connection with Input and Output separately by binding the server and the global object for Input and Output separately using each their own port number:

# PLAXIS 2D and PLAXIS 3D
# [...] 
localhostport_input = 10000 
localhostport_output = 10001
from plxscripting.easy import *
s_i, g_i = new_server('localhost', localhostport_input, password='yourpassword') 
s_o, g_o = new_server('localhost', localhostport_output, password='yourpassword')

Troubleshooting

If your script gives an error, please check the following:

• Is the PLAXIS application running?
• Is the Remote Scripting server inside PLAXIS activated with the same port number as used in the Python script?
• Is the firewall blocking communications with the PLAXIS application?
• Is the password given to new_server the same as the one in the 'configure remote scripting server' dialogue?

For more details on this Python wrapper and some code examples, please see the appendix on the Python HTTP REST API wrapper in the PLAXIS Reference manual and the related links.