How to set VT preferred instance and move to another VT

Epec Programming and Libraries Manual

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Supported platforms: CODESYS 2.3

How to set VT preferred instance and move to another VT

This guide describes how to:

set VT preferred instance

save used VT instance to nonvolatile memory

move to another VT on-fly

The following example assumes that MultiTool Creator code template is used and ISOBUS is initialized to CAN2.

Requires ISOBUS VT library 1.4.9 or later.

Variable definitions

The following example uses 3000 series FRAM to save VT instance.

FRAM definitions:

G_VTPreferredInstance AT %MB10006:BYTE := 0;

The following variables are used to trigger move to another VT.

Implementation to VT object pool is required (e.g. buttons or softkeys) and not described in this example.

Definitions:

G_MoveNextVT: BOOL := FALSE;

G_MovePreviousVT: BOOL := FALSE;

Set VT preferred instance

The following code sets the VT preferred instance which VT tries to connect to.

The FRAM variable is used as initial instance value.

The max wait time is application specific.

Application can utilize the terminal's boot time value from VT client metrics or implement wait time adjustment to object pool.

ISOBUS_CAN2_IsobusVtInitUserCode:

ISOBUS_VT_SetPreferredInstance(

i_pVTClient := G_ISOBUS_CAN2_Data.pVtClient,

i_PreferredVT := G_VTPreferredInstance,

i_MaxWaitTime := T#30s

);

Save used VT instance to nonvolatile memory

The following example code saves the VT instance to FRAM variable after VT client has connected to server.

ISOBUS_CAN2_IsobusVtUpdateUserCode:

(*Save current VT instance as preferred*)

IF G_ISOBUS_CAN2_Data.pVtClient <> DWORD#0 THEN

IF G_ISOBUS_CAN2_Data.pVtClient^.o_VtStatus.ObjectPoolReady THEN

IF G_ISOBUS_CAN2_Data.pVtClient^.o_VtStatus.VtInstance <> G_VTPreferredInstance THEN

G_VTPreferredInstance := G_ISOBUS_CAN2_Data.pVtClient^.o_VtStatus.VtInstance;

G_3724_FastParamsSave := TRUE;

END_IF

Move to another VT

The following code implements "Move to another VT" functionality which is used on-fly to move UI in different terminal.

The example implements move to next and move to previous VT.

Application can use o_AvailableVTs.MultipleVTs flag to check if multiple VTs are found before showing the move options to user.

Requires multiple VT terminals on ISOBUS.

It is also possible to move to specific VT instance number.

VT client has list of detected VT instances in o_AvailableVTs.InstanceFound array.

Moving to specific instance is not implemented in this example.

ISOBUS_CAN2_IsobusVtUpdateUserCode:

(*Move to another VT*)

IF G_MoveNextVT OR G_MovePreviousVT THEN

IF G_MoveNextVT THEN

movetype := ISOBUS_VT_MOVE_TO_NEXT;

ELSIF G_MovePreviousVT THEN

movetype := ISOBUS_VT_MOVE_TO_PREV;

END_IF

G_MoveNextVT := FALSE;

G_MovePreviousVT := FALSE;

move_result := ISOBUS_VT_MoveToAnotherVT(

i_pVTClient := G_ISOBUS_CAN2_Data.pVtClient,

i_Type := movetype,

i_PreferredVT := G_VTPreferredInstance,

i_MaxWaitTime := T#10s

);

END_IF