First time using monero. I sent a payment to an address. There was no mention of a payment ID from the receiver, but I decided to include an 8-digit payment ID anyway and sent to their address with my made-up payment ID. Will my payment go through, or did I just send it to the void? I told the recipient the payment ID, but I'm afraid that by including the payment ID in the first place, I modified the address. This was from coinex. Shouldn't the page have stopped me if I entered an invalid payment ID (8-digit)? I have since read that payment ID must be 16 or 64 digits.
If your exchange allows you to input a payment ID somewhere, they should be dealing with it appropriately. This means they should ensure it is the correct length / format and they should set it on the transaction correctly. When you executed the transfer, the exchange should also have given you a transaction ID which you can search for on a blockchain explorer such as xmrchain.net. Lastly, including a payment ID does not affect the destination. Whether you included a payment ID or not, your recipient should still receive the funds.
you can generate payment id randomly as mention in this link https://web.getmonero.org/resources/moneropedia/paymentid.html.
as of my experience you only got 8 bytes (16 length) of payment id when you generate integrated address but when you use transfer you need 32 bytes (64 length). you can generate 32 bytes of random hex and use as payment id.