Commonly used P&ID symbols (Piping and Instrumentation Diagram symbols) for instrument signals. Note that they may differ slightly from one project to another.
| Process Connection |  |
| Electric signal |  |
| Capillary connection |  |
| Software signal |  |
| Mechanical link |  |
| Hydraulic signal |  |
| Pneumatic signal |  |
| Electric binary signal |  |
| Pneumatic binary signal |  |