Special Application Modes

In the iSMA-B-W0202 module, simple applications are built-in, which can be used to control building devices. The applications provide logic between a signal from the special inputs and control digital output’s state. Relation between inputs and outputs is shown in the table below and it cannot be changed.

Special inputs can be set to work in different modes. There are dedicated registers for operation mode (40176, 40180), time parameters (40177, 40181), setpoints for heating/cooling modes (40178, 40182), and for a differential value in heating/cooling modes (40179, 40183).

Operation Mode Registers (40176,40180)

The register contains information about module working mode. Available modes and register values are shown in the table below:

Operating mode can be changed by writing right value in the Operation Mode register.

Special modes are initialized after 3 seconds from power up or restart of the module (the time value needed to stabilize the analog transmitter working).

Each input mode change sets assigned output to default state and resets the timer (used in time-based modes). If the new selected operating mode is running, the output is controlled according to the new mode functioning.

Ordinary IO

In this mode, the module works as a standard IO module, inputs and outputs are not related with each other.

Monostable Relay

In this mode, both rising and falling edge on the special input change the output state. The action of monostable relay can be executed remotely by changing the state of bit from false to true in the Command register (40020). Outputs can be also overwritten by the Digital Oouput register (40018), which allows remote control from BMS.

Bistable Relay

In this mode, only the rising edge on the special input changes the output state. The action of bistable relay can be executed remotely by changing the state of bit from false to true in the Command register (40020). Outputs can be also overwritten by the Digital Output register (40018), which allows remote control from BMS.

Time Relay NO [ms]

In this mode, if the output value is false, the rising edge on the special input sets the output to true. Every falling edge on the special input starts the counter from the beginning, which means that the output will stay true for a time defined in the Time Value register (expressed in milliseconds), counting from the last falling edge of the special input. The time relay action can be executed remotely by changing the state from false to true in the relevant Command register (40020). Outputs can be also overwritten by the Digital Output register (40018), which allows remote control from BMS.

Time Relay NC [ms]

In this mode, if the output value is false, the falling edge on the special input sets the output to true. Every rising edge on the special input starts the counter from the beginning, which means that the output will stay true for a time defined in the Time Value register (expressed in milliseconds), counting from the last rising edge of the special input. The time relay action can be executed remotely by changing the state from false to true in the relevant Command register (40020). Outputs can be also overwritten by the Digital Output register (40018), which allows remote control from BMS.

Time Relay NO [s]

In this mode, if the output value is false, the rising edge on the special input sets the output to true. Every falling edge on the special input starts the counter from the beginning, which means that the output will stay true for a time defined in the Time Value register (expressed in seconds), counting from the last falling edge of the special input. The time relay action of can be executed remotely by changing the state from false to true in the relevant Command register (40020). Outputs can be also overwritten by the Digital Output register (40018), which allows remote control from BMS.

Time Relay NC [s]

In this mode, if the output value is false, the falling edge on the special input sets the output to true. Every rising edge on the special input starts the counter from the beginning, which means that the output will stay true for a time defined in the Time Value register (expressed in seconds), counting from the last rising edge of the special input. The time relay action can be executed remotely by changing the state from false to true in the relevant Command register (40020). Outputs can be also overwritten by the Digital Output register (40018), which allows remote control from BMS.

Input Forwarding

In this mode, any signal from the input is transferred directly to the assigned output without any modifications. The input forwarding mode can be stopped by the Block Input function (see Blocking register).

Heating Mode

In this mode, the output is controlled as a typical thermostat, based on the Setpoint register and control value (input value) with differential parameter defined in the Differential register. The output signal works in 2 states, low and high.

If the control value is lower than or equal to the difference of the Setpoint register and Differential register, the output is in low state.

If the control value is higher than or equal to the sum of the Setpoint register and Differential register, the output is in high state.

Output in low state:

Control value >= Setpoint + Differential

Output in high state:

Control value <= Setpoint – Differential

The heating mode algorithm is shown in chart below.

Heating mode algorithm

WARNING!

In the case if the temperature sensor has failed (got disconnected or shortcut), then the heating mode does not work, and the output stays in the false state.

Cooling Mode

In this mode, the output is controlled as a typical thermostat, based on the Setpoint register and control value (input value) with differential parameter defined in the Differential register.

The output signal works in 2 states, low and high.

If the control value is lower than or equal to the difference of the Setpoint register and Differential register, the output is in low state.

If the control value is higher than or equal to the sum of the Setpoint register and Differential register, the output is in high state.

Output in low state:

Control value <= Setpoint – Differential

Output in high state:

Control value >= Setpoint + Differential

The cooling mode algorithm is shown in chart below.

Cooling mode algorithm

WARNING!

In the case if the temperature sensor has failed (got disconnected or shortcut), then the heating mode does not work, and the output stays in the false state.

Command Register (40020)

The module has a special Command register (40020). The Command register is used to remotely execute an action (simulate light switch/PIR). The action is executed by changing the state of relevant bit (changing from false to true). All special application modes can be executed, except Input Forwarding, Heating and Cooling modes.

Block Inputs Register (40021)

The Block Inputs register is used to block physical inputs signals to take action in logic. By setting true value on the relevant bit, the module blocks the input and no action will be executed. Setting false value restores normal operation. The Block Input function does not work when the heating/cooling input mode is set.

Setpoint Registers (40178, 40182)

The Setpoint registers contain values, which are used in heating/cooling modes as the setpoints for heating/cooling control algorithm.

The default setpoint value is 21.

The register stores the setpoint multiplied by 10.

Differential Registers (40179, 40183)

The Differential registers contain values, which are used in heating/cooling modes as the differential for heating/cooling control algorithm. Setpoint registers and Differential registers create deadband of the control values, which has no influence on output.

Deadband = (Setpoint – Differential, Setpoint + Differential)

The default differential value is 1 (read more in Heating mode and Cooling mode sections).

The register stores the differential multiplied by 10.