Trends

Trends – Connecting Live Data from CODESYS (Generate Code Documentation)

This guide explains how to use the “Generate Code” button to connect live data from a PLC – e.g., a CODESYS project – to the PLCVisu Trend module. The goal is to cyclically write measured values (e.g., temperature, pressure, fill level) to a database, which is then visualized in the Trend Viewer.

Purpose

• Automatically write live data from CODESYS to a trend database
• Visualize that data in real time on an HMI (e.g. WAGO WP400)
• Minimal setup effort thanks to the built-in code generator in PLCVisu

Step-by-Step Guide

1. Generate Code

Click the “Generate Code” button in the Trend UI. The code will be automatically copied and can be pasted directly into your CODESYS project.

(* DECLARATION SECTION *)
trendsFBlinetrend1Instance: PLCVisu.trendsFB; (* FB instance for current trend *)
slinetrend1Columns:STRING(4096):= 'dataset1';
slinetrend1Values:STRING(4096);
(* CODE SECTION *)
(* Initiate the instance parameters: path_to_file, max_records (cyclic buffer) *)
trendsFBlinetrend1Instance.init('$$PLCVisuDB$$/trends/linetrend1.db', {{max_records}});
(* write one record into the DB *)
slinetrend1Values := PLCVisu.ELA_UTIL.CONCAT_4096('"', REAL_TO_STRING({{dataset1_value}}));
slinetrend1Values := PLCVisu.ELA_UTIL.CONCAT_4096(slinetrend1Values, '"');
trendsFBlinetrend1Instance.write('',slinetrend1Columns, slinetrend1Values);
(* write delimiter line - optional - i.e. end of the batch -> this will cut the line in front-end view *)
(* trendsFBlinetrend1Instance.writeFinish(''); *)

Optional:
Use writeFinish('') to insert visual divider lines in the frontend view (e.g., to mark batch transitions).

2. Insert Your Sensor Variable

Replace {{dataset1_value}} with your real PLC variable, for example:

REAL_TO_STRING(GVL.TemperatureSensor1)

Notes:

• The variable must be declared as REAL
• For other types, use the appropriate converter:
  • INT_TO_STRING(...) for integers
  • BOOL_TO_STRING(...) for booleans, etc.

3. Connect CODESYS & PLCVisu

To allow PLCVisu to access the data, configure the connection as follows:

In CODESYS:

1. Open the Symbol Configuration
2. Mark the relevant GVL variables
3. Enable “Access Rights”
4. CODESYS Download

In PLCVisu:

1. Requirement is the setup of the connection string "eth" -> Go to connections...
2. Simply go to the editor to a Pages, then select a Control and click on the Connection String application. Then a window will open up, and to see your CODESYS data simply click on the top right green button to refresh, and then you'll see your edit CODESYS data.

4. Initialize the Database

In CODESYS:

trendsFBlinetrend1Instance.init('$$PLCVisuDB$$/trends/linetrend1.db', 10000);

• Creates (or opens) the database file in the trend directory
• 10000 defines the maximum number of stored records
• Must be called once before .write() – e.g., during project initialization

5. Write Values Cyclically

In CODESYS:

The following example writes the current sensor value during each cycle:

slinetrend1Values := PLCVisu.ELA_UTIL.CONCAT_4096('"', REAL_TO_STRING(GVL.TemperatureSensor1));
slinetrend1Values := PLCVisu.ELA_UTIL.CONCAT_4096(slinetrend1Values, '"');
trendsFBlinetrend1Instance.write('', 'dataset1', slinetrend1Values);

Caution: this function should be called in a very lw preority task, because otherwise the realtime behavior of the other Programm code can be destroyed.

Typical use case:

• Called within a cyclic task (e.g., every 1 second)
• Or triggered via a timer function block

Summary: CODESYS ↔ PLCVisu Trend

Troubleshooting

Recommendation

• Use the generated code as a template – adjust dataset1, variable names, and file paths as needed
• Need multiple signals? → Use multiple .write() calls or define dataset2, dataset3, etc.
• Test your trends with a single REAL variable first before scaling up