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CM10A serial controller RJ10 pinouts

Greetings:

I needed to build a custom serial interface cable for the CM10A (also known as IBM 75H8381) 2-way serial x10 controller; the reference material on the 'Net describes the connector as RJ11 and numbers the pins 1 through 4; only 6-pin RJ11 connectors have a pin 1 and the four pin versions are numbered 2 through 5. In fact the CM10A uses an RJ10 connector which is numbered from 1 through 4. Here are the signal assignments for this connector:

---------------------------------------------------4 Signal GND | ------------------------------------------------3 TxD | | ---------------------------------------------2 RI | | | ------------------------------------------1 RxD | | | |

-------------- | ! ! ! ! | | | |_ _| Plug, front end view |_ _| !--!

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Regards,

Michael Grigoni Cybertheque Museum

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It has come to my attention that there is a (later?) version of the CM10A which _does_ have an RJ11 6-pin connector:

"IBM 2-way Plug 'n Play Serial Interface", "Type HD16A 12J5976"

Evidently this version also has some EIA flow control lines.

Regards,

Michael

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Some of your confusion may be due to the fact that there is no such thing as a 6 pin RJ 11, it is really called an RJ-25. Also, the pins are numbered from the middle out.

Take a look at:

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snipped-for-privacy@waste.org wrote:

Reply to
Bob

I've seen that numbering scheme as well, but I will quote from the Data Communications PAL Engineering Reference:

There are four basic modular jack styles. The 8-position and 8-position keyed modular jacks are commonly and incorrectly referred to as RJ45 and keyed RJ45 (respectively). The 6-position modular jack is commonly referred to as RJ11. Using these terms can sometimes lead to confusion since the RJ designations actually refer to very specific wiring configurations called Universal Service Ordering Codes (USOC). The designation 'RJ' means Registered Jack. Each of these 3 basic jack styles can be wired for different RJ configurations. For example, the 6- position jack can be wired as an RJ11C (1-pair), RJ14C (2-pair) or RJ25C (3-pair) configuration...

The diagrams accompanying the explanation depict all physical jacks and pin assignments; although pair assignments may be built-out from the center, pin numbering remains the same as is depicted in my previous post.

Regards,

Michael

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