How to send commands and data upon request

Hello guys, 

I have gpib-usb-hs+ module and I am required to send the following commands and data in the following sequence:

MLA18

{DATA} (6 BYTES)

UNL

MTA18

{DATA} (5 BYTES)

UNT

I need this exact sequence with no UNL or UNT at the beginning or the end where they are not a must.

Currently each time I send MLA my program sends automatically send UNL.

I have tried to use c# library and ATEasy programming.

Would be very glad to hear your opinion on this issue).