The cFos Charging Manager allows the dynamic evaluation of formulas. This functionality is available for a meter of the type "Expression" and for charging rules of the type "Formula".

You can therefore set up meters that calculate values from other meters or EVSEs and keep them ready and display them. The charging rules can also use formulas to dynamically calculate the charging current and also access meters and EVSEs (including meters of the "Expression" type).

The following operations are possible with the formulas:

`+ - * /` | Addition, subtraction, multiplication, division |

`^` | Power calculation, e.g. 10^2 = 100 |

`min(x,y)` | Minimum of x and y, more than 2 arguments possible |

`max(x,y)` | Maximum of x and y, more than 2 arguments possible |

`abs(x)` | Absolute value of x, e.g. abs(-2) = 2 |

`sqrt(x)` | Square root of x |

Furthermore, the following logical expressions are possible:`==`

(equal), `!=`

(unequal), `<`

(less), `<=`

(less-equal), `>`

(greater), `>=`

(greater-equal), `!`

(not), `||`

(logical Or), `&&`

(logical And), `?`

(conditional operator, e.g. `x ? y : z`

, returns y if x is true, otherwise `z`

)

This allows, for example, the current to be switched off depending on conditions: `M1.current >= 6500 ? M1.current : 0`

returns the current of M1 if it is greater than 6.5A and 0 otherwise, which pauses the charging. For such conditions, it is also possible to query inputs (see below)

The following names are possible:

Mx | Meter with unit ID x, e.g. M1 |

Ex | EVSE with device ID x, e.g. E1 |

It is also possible to access virtual meters, such as solar surplus, grid draw or "Power avail. for EVSEs", by setting up the meter and then using the corresponding device ID in the formula.

You can then access individual values of the units by means of the point. These are called as follows:

current_l1 | Current of phase 1 in mA |

current_l2 | Current of phase 2 in mA |

current_l3 | Current of phase 3 in mA |

current | Current of the current phase in mA (for charging rules, the Charging Manager queries all phases one after the other; for meters of the type "Expression", the respective phase to which the formula refers applies. If you have specified a formula for "Current L1", you can omit the fields for Current L2 and L3. Then the formula for current L1 is used) |

power_va | Current power in Watt/VA (depending on the meter type, apparent power or active power can be supplied here) |

power_w | Current active power in watts |

opower_va | Wallbox: Current power offered in VA related to all 3 phases. |

import_wh | Energy drawn in Wh |

export_wh | Injected energy in Wh |

dt | The time that has elapsed since the last past update (in seconds) |

inputN | Input number N of the unit, 1 = active, 0 = inactive |

soc | SOC, charge level in percent (meter/storage) |

txn_duration | Duration of the current transaction in seconds (EVSE) |

txn_energy | Charged energy of the current transaction in Wh (EVSE) |

min_current | Minimum charging current in mA (EVSE) |

max_current | Maximum charging current in mA (EVSE) |

state | Status: 1 waiting, 2 plugged in, 3 charging, 4 charging with ventilation, 5 error, 6 offline (EVSE) |

M1.current_l1 | Current of meter M1, phase 1 |

E2.import_wh | Consumed Wh of the EVSE E2 |

E3.power_va | Current charging power from E3 |

If you use the formulas for a meter of type "Expression", you can also omit the device ID. Then the field names refer to this meter, e.g. 'power_va' is then the power of this meter in Watt/VA. You can use 'dt' to realise a few extended functions, e.g. in a meter of the type "Expression":

**As a formula for 'import_wh'**:`import_wh + M1.power_va * dt / 3600`

updates the sourced energy based on the power during the past update time**As a formula for 'power_va'**:`(power_va * (20 - dt) + M1.power_va * dt) / 20`

smoothes the power over the last 20 seconds.

**date**

date.year | Current year |

date.month | Month from 0..11 |

date.day | Day from 1..31 |

date.weekday | Weekday Mo=0, Tue=1, ... Sun=6 |

date.yearday | Day in the year from 0..366 |

date.hour | Hour from 0..23 |

date.minute | Minute from 0..60 |

date.second | Second from 0..60 |

date.daysecond | Second of this day from 0..86399 |

date.dayminute | Minute of this day from 0..1439 |

date.dst | 0 = winter time, 1 = summer time |

**PB** (cFos Power brain only)

PB.input1 | S0 Input 1, 1 = active, 0 = inactive |

PB.input2 | S0 Input 2, 1 = active, 0 = inactive |

**CM** Charging Manager variables

These variables can be set by the admin under "Configuration". For example, if the admin sets the variable 'var_x' to 1.5, CM.var_x returns the value 1.5.

Predefined variables:

_num_charging: Number of wallboxes currently charging

_num_charging1: Number of currently charging wallboxes, 1 if none is charging

_max_total_power: Maximum power of the house connection in W

_max_total_evse_power: Maximum power for the EVSEs in W

**Benutzung der globalen Objekte**:

charge 8A starting at 8:00am: `date.dayminute >= 480 ? 8000 : 0`

charge 16A on Saturday and Sunday: `date.weekday == 5 || date.weekday == 6 ? 16000 : 0`

charge 6A if input 2 active: `PB.input2 ? 6000 : 0`

charge 6A if CM variable non-zero: `cm.var1 ? 6000 : 0`

You want to additionally limit the charging current with regard to a consumption meter of a flat. To do this, you can set up a charging rule with the formula `16000 - M1.current`

.**M1** is the meter that measures the consumption of the flat. The load management of the cFos Charging Manager first tries to provide the EVSE with the maximum current in relation to the house connection power, but then limits this to **16A** minus the consumption of the flat.