1769-ECR... are they required??

LoganB

Lifetime Supporting Member
Join Date
Apr 2017
Location
Michigan
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607
In normal operation, obviously, we need an ECR for our compact logix to be happy and safe.

In a lab setting, just to do a quick test of an IO card, is there any way to jumper the end of the compact logix block to fool it into thinking there is an ECR in place? I literally have a 20 second test to do and don't want to spend $20 and three days to do it.

TIA!
 
Just inhibit the I/O Connection for the module to run the program but do you need to test I/O on this module?

G.
 
In general, the 1769 IO bus won't run properly without an end cap, unless the moon is full and your St. Christopher medal is fully charged.

The end cap is not complicated: it consists of just four resistors, but the wiring of them I had to probe with a meter.

R1 = 1000 ohms
R2 = 120 ohms
R3 = 1000 ohms
R4 = 330 ohms

R1 is between pins 2 and Outer Plane (3,5,8,9)
R2 is between pins 2 and 10
R3 is between pins 10 and Inner Plane (1,11,14,16)
R4 is between pins 13 and Inner Plane (1,11,14,16)


If I was just guessing and had only one resistor in my desert island, I would put 120 ohms between pins 2 and 10 because that's a typical CAN termination.

1769ECR.jpg
 
Saving this one for next time I get stuck in rural China with no end caps and a deadline!

Also, if I'm ever stuck on a desert island with only an Allen-Bradley PLC to signal for help, I want Ken with me.
 
That's great info Ken, thanks.

Now I'm really curious to "see" someone, LoganB?, attempt an ad hoc end cap. Would the CAN termination be enough I wonder? Are the others just window dressing like surge suppression? The 120 ohm makes sense as the 5.1vdc CIP bus is effectively riding on CAN.

What could go wrong?...

In the interest of us all learning - take one for the team and try it!

G.
 
Welp, was not a perfect test environment. I didn't have a 120 ohm resistor on hand, so I had to use two 220 ohm resistors in parallel, though not sure if 110 ohms is close enough to work (should work within the range of 108-132 ohms iirc?). I was able to get the IO to be happy for about two seconds, then the resistor pin slipped off the plug pin, and I wasn't able to get it to work again. If I can get my hands on a 120 ohm resistor and maybe a spare 16 pin female plug to make it easier to keep contact with the correct pins, I will attempt this again! If anyone else tries, let us know what you find out!
 
No issue finding the hardware itself! I'll just have to do it at my lab instead of at my work. My boss has minimal patience for "projects" that he doesn't assign himself :ROFLMAO:
 
interesting thread, I also have the same question
o.png
 

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