Null Modem Cable（交叉串口线） [复制链接]

原文： https://www.m0yom.co.uk/when-a-null-modem-cable-is-not-a-null-modem-cable/

ACOM Director作者写的关于交叉串口线（也叫NULL MODEM CABLE）的帖子，放上来供查阅。

有时候网上买到的交叉串口线，不好使，就要检查一下是否买到了有瑕疵的线了。

下面第一张图，才是最完全的交叉串口，第二张图，仅仅交叉了TXD和RXD，这种线，有些软件可以正常工作，但有些不行。

While working on the next update to ACOM Director Plus (yes, work is now continuing on it), I couldn’t figure out why my code to turn on the ACOM600S was not working. I’d previously put this down to the fact that I have an early model and perhaps this wasn’t implemented then. I resorted to using my scope to check that the DTR and RTS lines were in fact being activated properly which is when I discovered that my Null Modem cable i’d been using for years now is not in fact a proper Null Modem Cable.
A normal (proper) Null Modem cable has the following wiring, notice the crossover of the DTR & DSR pins and the RTS & CTS pins, these are used for the remote power on of the ACOM600S, ACOM1200S and ACOM2000A with the RPON Module.

However after checking the wiring on my (commercially purchased) Null Modem Cable, I found it is actually wired like this.

As pins 2 & 3 are crossed, it still works fine for normal serial communications (without handshaking obviously) however all other pins are straight through, so anything relying on the proper use of handshake signals will fail.
The moral of the story, if you have issues with remote power on of the ACOM600S, ACOM1200S or ACOM2000A (or anything else that makes use of any control pins), make sure your Null Modem cable is actually wired fully to the Null Modem standard and not a half baked cable like mine.

雪中送炭啊！！

ACOM Director Plus，支持ACOM 600S和ACOM 1200S
ACOM Director Classic，只支持ACOM 2000A ACOM Director Classic 0.8.1.zip (626 K) 下载次数:2 ACOM Director Plus 0.6.0 (Beta).zip (1171 K) 下载次数:3

YAESU 的机器的COM使用的是直连线。用过一次交叉的不好用。

淘宝上力特有这样的线：

https://detail.tmall.com/item.htm?spm=a230r.1.14.101.26af74e6tqZYvX&id=585282395282&ns=1&abbucket=6&sku_properties=148242406:65793

如果连接没有了，所搜 Z-TEK 力特 串口 交叉线
型号分别是：ZC291 ZC295 ZC297 ，长度不一样

老板试验成功没有？