An interface to 3270 displays would be useful only if you had software that supported 3270 on your platform. Further, is there a real 3270 that is less expensive than running, e.g., TN3270, on a desktop?
RS-232-C is just a protocol between a serial adapter and a modem; it doesn't specify, e.g., control characters, packets, going between the modems. B&T, Ethernet and TR all specify controls at a higher level. Your best resource for 3270 information is probably bitsavers. -- Shmuel (Seymour J.) Metz http://mason.gmu.edu/~smetz3 ________________________________________ From: IBM Mainframe Discussion List <[email protected]> on behalf of Alexander Huemer <[email protected]> Sent: Tuesday, January 14, 2020 4:52 AM To: [email protected] Subject: Talking to 3270 terminals? Hi I am new to this list and would like to discuss an idea and ask several questions. * Did anybody ever attempt to 'talk' to 3270 terminals with something different than an IBM mainframe? This might sound like a strange idea, though I find it intriguing to be able to display content on such a terminal and be able to receive keyboard input from it. I guess the most straight-forward way to attempt something like that is to use a 3270 terminal attached to a 3174 or similar and try to talk to that instead of the terminal itself. I wouldn't know how to interface with the terminal directly over the coax. * What's the best available documentation regarding 3174 models and their features? I poked around on ibm.com and google but wasn't able to find much. It seems like there were several different physical-layer north-bound interfaces for 3174. Bus&Tag, Token Ring, Ethernet, RS232 (if I am not mistaken, for dial-up connections), maybe others? Bus&Tag doesn't seem to be a good candidate, it's difficult to interface with as far as I understand. Ethernet is way more common these days than Token Ring, though TR NICs are easy to procure second hand and protocol support under Linux (the OS I am most savvy with) is in place. RS232 is easy to interface with also, though then again, I am not sure if that interface really exists. * Did the LAN interfaces (Ethernet, TR) talk SNA on layers 2 and 3 or was there by any chance something going on with TCP/IP? I doubt it though. Talking SNA with custom software doesn't seem to be a low-hanging fruit. >From where I stand right now I cannot say how straight-forward the network traffic between the mainframe and a 3174 is, how difficult it would be to emulate that protocol with custom software over several layers. * Is anybody on the list here able to provide protocol traces from the link between mainframe and 3174 over any interface? pcap format is preferred, though anything would be valuable. I would appreciate any thoughts regarding this topic, especially to the questions marked with asterisks. Also, if anything is known regarding a similar thing with 5250 instead of 3170 terminals, that would be interesting as well. -Alex ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
