Unable to locate element error while trying to locate an input box element using Selenium through Python

Looking at the html, id mentioned can be dynamic, so you can't put the static id in your identifier.
However, as name attribute is present in the html, you can use that to identify your element, like:

browser.find_element_by_name("PURCHASE_ORDER_CODE_NAME").click()

Updated answer as per discussion with the OP

As an iframe is present on the UI, you need to first switch to the iframe and then click on the element.
To switch to iframe you can use:

browser.switch_to.frame(browser.find_element_by_tag_name('iframe'))

and then use:

pc = browser.find_element_by_name("PURCHASE_ORDER_CODE_NAME")
pc.click()
pc.send_keys("7555425-1")

if you want to switch back to the default content, you can use:

browser.switch_to.default_content()

The desired element is a dynamic element so to invoke click() on the element you have to induce WebDriverWait for the element to be clickable and you can use either of the following Locator Strategies:

• Using CSS_SELECTOR:

  WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.CSS_SELECTOR, "input.x-form-field.x-form-text[id$='-input'][name='PURCHASE_ORDER_CODE_NAME']"))).click();
  

• Using XPATH:

  WebDriverWait(driver, 20).until(EC.element_to_be_clickable((By.XPATH, "//input[@class=' x-form-field x-form-text ' and contains(@id,'-input')][@name='PURCHASE_ORDER_CODE_NAME']"))).click();
  

• Note : You have to add the following imports :

  from selenium.webdriver.support.ui import WebDriverWait
  from selenium.webdriver.common.by import By
  from selenium.webdriver.support import expected_conditions as EC
  

Maybe you can try another "selector" approach. Ex(Javascript):

selenium.By.xpath('//*[@data-icon="edit"]')
driver.findElement(by).click()