# Selection via HMI interface

The operator sets the syntax check as an operating mode before starting the program. This setting is forwarded to the PLC via a control unit which the PLC can permit or reject.

The syntax check can be selected using the PLC without any previous request from the HMI.

Parameter | Description
mc_command_execution_mode_r, mc_command_execution_mode_w | Selecting syntax check
mc_active_file_offset_r, mc_active_file_name_r | Displays the current file position during the syntax check at the decoder level.
mc_command_single_block_w | This parameter selects the decoder single step mode in the syntax check.

Syntax check via HMI
Description | A user interface can select the syntax check via this interface. At the same time, the dry run mode must always be selected together with the syntax check.
Type | 32 Bit
Value range | 0x0000 ISG_STANDARD Normal mode 0x0008 SYNCHK Syntax check simulation 0x0040 MACHINE_LOCK Dry run without axis motion
HMI elements | mc_command_execution_mode_r, mc_command_execution_mode_w
Access | Read, write
IndexOffset | 0x40, 0x3f (IndexGroup = 0x000201<ii> where <ii> = channel)