Typical input blocks for normal mode

The present normal plant operating mode 1...16 is determined by evaluating the applicable input blocks.

A selection from the following input blocks is typically used:

Manual switch, e.g. operating mode switch, or 'On' / 'Off'
Software switch
Scheduler program
Demand signal, e.g. from a VAV plant and room control

Input blocks for normal mode in the Programming editor

① Normal mode
② Exception mode (rapid shutoff of the normal mode for an enabled exception mode)

Present plant operating mode determination

In this example, only plant operating modes 1 = 'Off' and 2 = 'On' are transmitted.
Up to 16 different plant operating modes can be transmitted to function block CMDSEQ_B.

The input blocks in the example are:

Manual switch with R_M
Software switch with R_M
Scheduler with R_MSCHED

The following information can be read via both function blocks W_M Write multistate:

Present operating mode
Reason for the present operating mode

Providing input block signals

The manual switch and the software switch provide an enumeration (1 = 'Auto', 2 = 'Off', 3 = 'On').
The enumeration is sent to function block SWICNV_M. It converts the signal as follows to an enable signal 0 or 1 on output [EnSwi] and a value 1 or 2 on output [ValSwi]:

[IN] = 1 "Auto" ➔ Enable [EnSwi] = 0 "No", [ValSwi] = 1 "Off"
[IN] = 2 "Aus" ➔ Enable [EnSwi] = 1 "Yes", [ValSwi] = 1 "Off"
[IN] = 3 "On" ➔ Enable [EnSwi] = 1 "Yes", [ValSwi] = 2 "On"

Function block SWICNV_M sends the signals [EnSwi] and [ValSwi] to function block ENSEL_MS.

The scheduler reads the value of the BACnet object Timeswitch and forwards the present state 1 = "Off" or 2 = "On" to function block ENSEL_MS.

Present signal selection

The selection of the present input block for consideration now occurs in function block ENSEL_MS. The active input with the lowest number [En1]...[En3] is used and its value is sent via the output [Value] to function block CMDSEQ_B.

In the example, this means:

If input [En1] has value 1 (manual switch to "Off" or "On"), the value of input [Val1] (1 = "Off" or 2 = "On") is forwarded to output [Value]. The other inputs [En2]...[En3] are not considered.
If input [En1] has value 0 (manual switch to Auto), this input is ignored and the next input [En2] is considered.
If input [En2] has value 1 (software switch to "Off" or "On"), the value of input [Val2] (1 = "Off" or 2 = "On") is forwarded to output [Value]. Input [En3] is not considered.
If input [En2] has value 0 (software switch to Auto), this input is ignored and the next input [En3] is considered.
The value on input [En3] is defined on the function block with 1, i.e. the scheduler is always active. The value of input [Val3] (1 = "Off" or 2 = "On") is forwarded on output [Value].