InfoPath does not allow you to use character limits on multiline boxes. You can however, work around this issue by using a validation rule that prevents a user from submitting a form when it exceeds a specific number of characters.
- Open the form in InfoPath
- Select the field you wish to limit
- On the Ribbon, click on Home -> Manage Rules
- Add a New Validation Rule
- Call it whatever you like, e.g. “CheckStringLength”
- Set the condition as follows:
where 250 is the character limit.
- The end result of your rule should look like this:
- Test your new validation rule by typing something that exceeds the number of characters you specified.
- A red box should appear around the field and you will not be able to submit the form until you correct it. It is advisable to include a tool tip to inform the user on the maximum number of characters.