# Virtual Variables P/I/F/IO

## Basics

`P1`, `I1`, and `F1` are variable names in the common interface. They are not internal UR Controller variables.

In the UR implementation, `RobotVarManager` saves them to JSON.

```text
P1
    ↓
RobotVarManager
    ↓
JSON
```

## Attribute access

```python
robot.P1 = [300, 0, 200, 0, 180, 0]
print(robot.P1)

robot.I1 = 10
robot.F1 = 1.5
```

## get_var() / set_var()

```python
robot.get_var("P1")
robot.set_var("P1", [300, 0, 200, 0, 180, 0])

robot.get_var("P", 1)
robot.set_var("P", 1, [300, 0, 200, 0, 180, 0])
```

## P variables

```python
robot.set_P(1, [300, 0, 200, 0, 180, 0])
pose = robot.get_P(1)
```

P is a six-element pose in mm / degree rotation-vector representation.

## teach()

```python
robot.teach("P1")
robot.teach("J1")
```

`teach("P1")` saves the current TCP pose as P1.

`teach("J1")` saves the current joint angles as J1.

This is teaching at the higher-level common interface; it does not write a P1 register in the UR Controller.

## I / F

```python
robot.set_I(1, 100)
robot.get_I(1)

robot.set_F(1, 1.25)
robot.get_F(1)
```

## IO

`IO` is not a virtual variable; accesses are forwarded to physical IO.

```python
robot.IO0 = True
print(robot.IO0)
```

Internally, `set_IO()` / `get_IO()` are called.

## is_empty_position()

```python
robot.is_empty_position("P1")
```

Returns True if the P variable has not been registered.