old Modicon PLC

[lalion]

Hi,

I have a customer with an ancient modicon plc that is not going into run mode, Gould Micro84 (M84A-002). I cant find any run switches on it and dont have the programming unit so cannot plug in and program, so its looking like I will need to put in a new plc.

This leads to my next problem, Ive been given a print out of the program and I/O, I can understand most of it but a couple things have caught me.
1) There are several internal memory registers that I cant find controlled anywhere, 2201, 2202, 2203, 2204. I can only assume these a dedicated registers for startup/etc?
2) There are a lot of rectangles drawn, which I assume are timers? Refer below diagram. Can anyone give insight to this logic, or show me where I can get documentation.

Thanks, Leon

------|
| 5 |
| |
|T0,1 |
| |
|4014 |
------|

 

[Jim Dungar]

Yes that is a timer, it is very similar to those used in 984 Ladder Logic. If you find any information on 984LL it will help you with your Micro84.

The timer needs continuous power to the two "input pins" on the left hand side. The upper right output pin is the Timed contact, the bottom right output pin says the timer is enabled. The top number is the preset and the bottom number is the register that does the timing.

In what context did you see your 2xxx registers? My memory says these were used as drum controllers, but I am not sure.

 

[lalion]

Hello Jim,

cant find any documention on either M84 or 984LL.

Many of the blocks dont have any rung attached to top right, and some are located on far right end of the rungs. Though these have 4001 written instead of T0,1 in centre.

the 2xxx registers are located throughout my rungs as N/O and N/C, shown as in series in many of the rungs. What do you mean by drum controller?

Thanks,
Leon

 

[TConnolly]

Look here for links to 984LL manuals:
http://forums.mrplc.com/index.php?dlcategory=25

 

[Jim Dungar]

All Modicon function look like blocks. different functions need connection to different input pins. Typical function blocks are: ADD(ition), SUB(traction), and BLKM (block move).

A drum controller is not a common command any more as it can be duplicated with register shift commands. The most common drum controller, in the real world, is a music box; a set of outputs operated in a repeatable pattern.