about that list ...
Noel,
you already have: 1785-L40C (PLC-5/40) Processor Module ... EXCELLENT! ... more horsepower than you’ll ever need for student training purposes ... also, this is an “enhanced” type processor so you’ll be able to program it with a simple (cheap) RS-232 connection - rather than being forced to use the expensive DH+ (Data Highway Plus) alternative required for the older “classic” type processors (example: PLC-5/15) ...
1 EACH 16 SLOT I/O CHASSIS, 1771-A4B ... excellent - again more room than you’ll ever need for training purposes ...
1 EACH PLC 2/30 PROGRAMMABLE CONTROLLER, 1772-LP3 ... as Jeff said, this is an older technology ... I wouldn’t recommend going out and looking for one but as long as it’s part of the package, you could always use it for a high-tech paperweight ... plus there are quite a few companies still using these old beasts - someday you just might be glad you have one around ...
1 EACH 120 VOLT AC POWER SUPPLY MODULE, 1771-P4 OR 1771-P4S ... excellent ... but you might have to buy a 120 volt connector for the power connection ... when systems are butchered, a lot of guys just rip out the plug and leave it hanging on the end of the wire ...
1771-OA, 120 VOLT AC OUTPUT MODULE ... good but only 8 outputs ... 1771-OAD would be better with 16 outputs ... still - if the price is right - go for it ...
1771-IA, 120 VOLT AC INPUT MODULE ... good but only 8 inputs ... 1771-IAD would be better with 16 inputs ... still - if the price is right - go for it ...
1771-IBD, 10 TO 30 VOLT DC INPUT MODULE - excellent ... this will give you 16 points of 24VDC input capabilities ... be aware that this is a SINKING type module - not a SOURCING type ... that means that your inputs must provide +24VDC to turn on the inputs ... so any 24VDC sensors that you eventually buy should be PNP or sourcing-type sensors ...
1771-OB, 12 TO 24 VOLT DC OUTPUT MODULE ... good but only 8 outputs ... 1771-OBD would be better with 16 outputs ... still - if the price is right - go for it ...
1771-OGD, TTL OUTPUT MODULE ... good ... but you’ll probably find very little use for this one ... TTL stands for “transistor to transistor logic” which basically means low voltage DC signals (something in the 0.5 to 5.5 volts range) ... even so, you can still control the 16 LED’s on the front of the module as part of your training experiments ... there’s no such thing as “too many” flashing lights on a student programming project ...
1771-IXC THERMOCOUPLE INPUT MODULE ... no such animal that I know of ... so you probably meant to say 1771-IXE ... if so, then EXCELLENT! ... very handy for temperature experiments ... just don’t rush out and buy expensive thermocouples to go with it - just get your hands on some of the thermocouple hook-up wire ... strip the insulation from about a half inch at the end and twist the two wires tightly together ... that will give you a dirt-cheap thermocouple that will work perfectly for student exercises ...
1771-IFC, ANALOG INPUT (12 BIT) MODULE ... no such animal that I know of ... so you probably meant to say 1771-IFE ... if so, then EXCELLENT! ... very handy for analog experiments ... we can talk about how to build bargain basement inputs as we proceed ...
1771-OFC, ANALOG OUTPUT (12 BIT) MODULE ... no such animal that I know of ... so you probably meant to say 1771-OFE ... if so, then EXCELLENT! ... very handy for analog experiments ... there are three types of these so be more specific from now on ... 1771-OFE1 gives analog voltage outputs ... 1771-OFE2 gives analog milliamp outputs (4 to 20mA) ... 1771-OFE3 gives analog milliamp outputs (0 to 50mA) ...
the last three (all analog) modules are excellent because they’ll give you the ability to learn about Block Transfer Reads and Block Transfer Writes ... a PLC-5 subject that most entry-level job applicants have little or no knowledge about ...
final thoughts ... do all of these modules still have their swingarms (terminal strips) with them? ... you’ll need these to make the electrical connections ... many bargain basement systems are butchered out of old machinery ... unfortunately the quickest way to rip out the equipment is to simply snap off the swingarms and leave them dangling on the ends of the cabinet wires ... you CAN buy the swingarms separately but they’re not cheap (about $40 each list price) and it’s a hassle to have to order them when all you want to do is to start playing with your new toys ...
all in all - it sounds like a lot of neat stuff - BUT if you didn’t already have that processor, I’d probably tell you to look a little bit further ... anyway you can send me the price in a private message if you like and I’ll let you know whether it sounds reasonable ... those last three analog modules alone might be worth what the seller is asking ...each one of those has a list price of around $1500 ... and there’s a LOT of student training horsepower right there ... far beyond flashing lights and pushbutton switches ...
