What is the difference between a straight-through and null modem serial cable? - StarTech.com IT Pro Community
<main> <article class="userContent"> <p>A straight-through serial cable is the most common type of serial cable, used to connect a Data Terminal Equipment (DTE) device (for example, a computer) to a Data Communications Equipment (DCE) device (for example, a modem). The pinout of the serial connectors on both sides of the cable are exactly the same with a straight-through serial cable.</p><p>A null modem serial cable (frequently called a crossover cable) is used to connect two DTE devices together without the use of a DCE device in between. For this to happen, the Transmit (TXD) and Receive (RXD) pins on one of the serial connectors are flipped.</p><p>To confirm the type of serial cable that is required for your device or configuration, refer to the information provided by the manufacturer.</p><p><br></p><p><br></p><div class="blockquote"><div class="blockquote-content"><p class="blockquote-line">This FAQ applies to these products:</p><p class="blockquote-line"><a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fat925ff" rel="nofollow noreferrer ugc">AT925FF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fat925fm" rel="nofollow noreferrer ugc">AT925FM</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fat925mf" rel="nofollow noreferrer ugc">AT925MF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fat925mm" rel="nofollow noreferrer ugc">AT925MM</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fat925sfm" rel="nofollow noreferrer ugc">AT925SFM</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fat925smf" rel="nofollow noreferrer ugc">AT925SMF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc258ff" rel="nofollow noreferrer ugc">GC258FF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc258mf" rel="nofollow noreferrer ugc">GC258MF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc25sf" rel="nofollow noreferrer ugc">GC25SF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc25sm" rel="nofollow noreferrer ugc">GC25SM</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc98ff" rel="nofollow noreferrer ugc">GC98FF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc98mf" rel="nofollow noreferrer ugc">GC98MF</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc99mfra1" rel="nofollow noreferrer ugc">GC99MFRA1</a> <a href="https://community.startech.com/home/leaving?allowTrusted=1&target=https%3A%2F%2Fwww.startech.com%2Fen-us%2Fcables%2Fgc99mfra2" rel="nofollow noreferrer ugc">GC99MFRA2</a> 9FMNM-3M-RS232-CABLE</p></div></div> </article> </main>