DO { WHILE | UNTIL Condition }
    Statement(s)
    { EXIT }
  LOOP

  DO
    Statement(s)
    { EXIT }
  LOOP { UNTIL | WHILE Condition }

Function
Create a repeating loop that executes the program lines between DO and LOOP, optionally testing before or after the loop statements.

• Condition  is a simple statement, such as "idx = 7" that can be evaluated as True or False. Only one comparison operator is allowed (see IF...THEN for valid condition operators).
• Statement  is any valid SX/B statement.

Explanation
DO...LOOP loops let your program execute a series of instructions indefinitely, or until a specified condition terminates the loop. The simplest form is shown here:

Alarm_On:
  DO
    HIGH Alarm_LED
    PAUSE 500
    LOW Alarm_LED
    PAUSE 500
  LOOP

In this example the alarm LED will flash until the SX is reset. DO...LOOP allows for condition testing before and after the loop statements as show in the examples below.

Alarm_On:
  DO WHILE AlarmStatus = 1
    HIGH Alarm_LED
    PAUSE 500
    LOW Alarm_LED
    PAUSE 500
  LOOP
  RETURN

Alarm_On:
  DO
    HIGH Alarm_LED
    PAUSE 500
    LOW Alarm_LED
    PAUSE 500
  LOOP UNTIL AlarmStatus = 0
  RETURN

When the second form is used the loop statements will run at least once before the condition test.

Related instructions: FOR...NEXT and EXIT