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Old July 5th, 2002, 04:21 AM   #1
iknowsomeplc
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Flex frequency input module - problem with encoder connection

We are using 1794 -IJ2 Flex IO modules for taking Encoder feedbacks from Hubner- Berlin Encoders. When we are connecting one channel , the readings are good. The supply voltage from the module - to - Encoder drops to 5.6 VDC but it still works and we get the readings OK. ( the 24vdc supply at the Power Supply end stilll measures 24VDC !!).
But the moment we connect 2nd encoder to 2nd channel , both the readings are gone . I understand that the supply voltage 24vdc folds back inside the module ( In IJ2 ,the encoder supply has to routed through the module only)

The details of Encoder Name Plate is :

HUBNER - BERLIN
MODEL : POG9GD 150
Incremental Encoder
9-30 VDC
IP56
Current Intake : 22 mA

Anybody knows solution for this?
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Old July 5th, 2002, 06:03 AM   #2
Terry Woods
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Is this the situation you are describing?



If so...

Then since the module voltage to the first encoder drops at all means that either...

1) the module can't supply the amount of current that the encoder needs. (a module problem)

-OR-

2) the encoder wants more current then the module can supply (an encoder problem)

So, which problem is it?

Insert a milliamp-meter between the module and the encoder.

If the current is greater than the specified 22mA then the Encoder is at fault - replace it.

If the current is substantially less than 22 mA then the Module is at fault - replace it.

It's an OHM's Law kinda thing.

You can't expect a device to deliver more power than it is capable of - it gets kinda tired (voltage drops).

At the same time, a down-line device should not demand more power (read that as more current, because of low resistance) than is available.

So, although the module and encoders seem to be "matched", one of them is not operating properly. You won't know which is failing until you read the mA.
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Old October 30th, 2009, 04:37 AM   #3
jainil2210
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Exclamation 1794-IJ2 frequency module.

Hello,
i'm planning to use 1794-IJ2 frequency module for the first time in my new project.
My questions are:
1)can i use this module in place of dynalco speed monitor?
2)is it necessory to connect 2 inputs in this module?cant i use single magnetic pickup probe as single input in this module?(as catalog says that this module calculate speed with two probes only.)
3)what is the difference between gate input and frequency input?can i connect any input to frequency input?
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Old October 30th, 2009, 10:18 AM   #4
Mickey
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Quote:
1)can i use this module in place of dynalco speed monitor?
Yes, but you will have to do some math to get speed. Module gives you frequency and direction.

Quote:
2)is it necessory to connect 2 inputs in this module?
No

Quote:
cant i use single magnetic pickup probe as single input in this module?(as catalog says that this module calculate speed with two probes only.)
Yes a single input is ok. Each channel has two inputs frequency and gate. Frequency input is used to calculate frequency and the gate input is used to determine direction.

Quote:
3)what is the difference between gate input and frequency input?
Gate input is used to determine direction.

Quote:
can i connect any input to frequency input?
Not sure what you mean here, see manual for devices that can be connected. Link below for manual.

http://literature.rockwellautomation...m011_-en-p.pdf
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