1774 PLC

[ptaylor 0]

Looking for some advise from any long in the tooth Allen Bradley experts. We have a customer with 1774 PLC, not sure of all the part numbers (tell me if this is significant to responding) The programme is loaded by means of a star-link tape recorder. Is there a better way of accessing the programme. I'm guessing that the serial connection to the tape deck is DF1 or DH. presumably there is an alternative means of uploading the programme or perhaps copying the tapes, if there is please advise. We have good knowledge of AB PLC's bcak to and including PLC2's, just throw any advise you thing might be useful. thanks

[Guest]

I used to work for an AB distributor ... we kept one of the old programming terminals on a back shelf ... once in awhile we'd lend/lease/rent/etc. it out to a customer who was in a bind ... I'd check with the local distributor if I were you ...

[newpageboba 7]

The good old days I grew up on the 1774 PLC with both 1778 & 1771 I/O. Most people at AB do not even know about the 1774. We had about 15 PLCs at our facility. We upgraded our last original PLC in 2001. So my memory is probably faded. OK. The only way the PLC will talk DH is with a datahiway card. Notice I said datahiway and not dataway plus. You could only program the PLC via a terminal (blue goose or 1770-T1) And could only save the program via a star link tape recorder through the terminal We had a Xycom PC for printing out the programs. But you could hook a serial printer to the terminal to print out a program with no descriptions. I would recommend upgrading to a PLC5 ASAP. You will have to write the program from scratch. The 1774PLC table is similar to the PLC2 5 digits, if it started with a zero it was an output if it started with a one it was an input if it started with a 2 or higher it is storage or timer/counter. 1774PLC also had rack 0 (PLC2 did not) The I/O communications is serial. To upgrade to a PLC5 would require running blue hose for the I/O communications, Pruchasing 1771-ASB modules for the remote racks & a PLC5 for Rack 0 This would allow the addresses to be similar. ex. input 11203 would become I:12/03 output 02415 would become O:24/15 But the best recommendation is upgrade. Edited 23 Sep 2008 by newpageboba

[ratcliffe_ic 2]

The ICOM PLC2 software has a facility to do something with 1774 PLC programs, I can't remember what exactly, it's 10 years since I last used it. Under F5 utilities you can monitor a PLC/PLC2 over DH. You can also upload from a tapedeck or cartridge to the software. I've a feeling we used to save the program to a tapedeck, then upload the tapedeck to the computer, then merge with comments and produce a printout for the maintenance guys. The ICOM software is not cheap though.

[Rod_Hackney 2]

I would be careful putting 1771-ASB modules and PLC5s into older racks. In the 90s, I did quite a few PLC2 to PLC5 conversions and ran into version compatibility issues on older hardware.

[Gerry 13]

The tape deck interfaces are serial RS-232. The 1770-SA (cassette tape) was fixed speed 1200 baud. The 1770-SB (cartridge tape) was switch selectable up to 9600 baud. Early PC software (Taylor, ICOM, etc.) could read the program from the tape deck and/or emulate the tape deck connected to port C on the the 1770-T1/2/3 terminal to save the program directly to disk. The 1774 was obsolete 25 years ago, the PLC-5 is very near obsolete now. You should be looking at moving to ControlLogix.

[jstolaruk 9]

Agreed. Gotta figure racks need to be swapped out when quoting. I did two plc-2 to plc-5 conversions last year (Logix wasn't an option) and the AB salesguy told me PLC5s have lots of life left in them and won't be fully silvered listed for years due to the installed base. Go figure.