What can be added to CPU1214 to read a line driver signal?

Drop in the signal board 6ES7-221-3AD30-0XB0 for 4xDI @ 5V.

Then configure the inputs to accept your encoder signals. 

trinhngocduy

 Hi,William_B

"Option 3 does not work for the CPU1214."

''One problem .. what voltages can your encoder handle? If it is 5V, then you have to use a special signal board.''

 Can you tell me the name of special  signal board?

I want use CPU1214 conecting incremental encoder with Line driver output type (5VDC)

Thank!

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Split from Need help with selecting encoder output type .

Reference on configuration settings here:

https://support.industry.siemens.com/tf/WW/en/posts/s7-1214c-plc-with-sb1221-hsc-configuration-and-enocder-hardware-connection/124001?page=0&pageSize=10

and here:

https://support.industry.siemens.com/tf/WW/en/posts/signal-board-5vdc-200khz/184992?page=0&pageSize=10

and this user solved possibly a similar problem:

https://support.industry.siemens.com/tf/WW/en/posts/s7-1214c-encoder-and-signal-board/119353?page=0&pageSize=10

With the line driver configuration from the encoder, you have several options:

1. Connect up just A / B and ignore A- and B- and use A/B counter or A/B counter fourfold
2. Connect A/B to I4.0/I4.1, and A-/B- to I4.2/I4.3, as 2 A/B counters (either fourfold or not)
3. Get a line driver converter that takes in the 4 A/A-/B-/B- signals and outputs just A/B @ 0-5VDC (or 0-24VDC).
4. Get a line driver quadrature to profinet converter like the SINAMICS drives often use for external or existing encoders with Siemens drives.
5. Get a line driver to anything that you feel comfortable connecting to your S7-1214.

As someone stated in one of the above forum posts, "Just hooked it up and it worked" (I paraphrased).

#dP

 Hello huggy_d1,

huggy_d1

Drop in the signal board 6ES7-221-3AD30-0XB0 for 4xDI @ 5V.

Then configure the inputs to accept your encoder signals. 

How is the connection made between a encoder with line-driver / differential signals and the signal board?

Thanks in advance.

It really depends on the encoder.  There are some encoder manufacturers that do not protect their output circuits at all (very popular as well).  Robust is not the word you use.  The word you use is.... popular.... :)

Several encoder manufacturers protect the outputs from bad wiring (or bad designs).

My suggestion would be to connect the encoder's power supply common (what it uses for the mid-point of the A/A- & B/B-) with the 24V supply common.

If the encoder quits working and you do not have a spare on hand, you may be waiting longer than you would like for another one.

One option I personally have used is an encoder signal conditioner.  Take in A/A-/B/B- (and Z/Z- if available) and output TTL level signals for A/B (Z).

The encoder signal conditioner is often more expensive than getting a robust encoder that outputs what your PLC can handle natively.

Did you know Siemens makes both Profinet encoders AND robust encoders that output 24VDC (among others)?

#dP

Hello huggy_d1.

Please allow me to voice my concern about using the CPU1214 and related hardware for the task.

A differential signal wave has a +5V or -5V potential between the positive and negative phase pair. A line driver circuit is only concerned with the relative voltage drop in the phase pair.

The voltage drop between the signal ground (on the PLC) and any of signal pairs is undetermined. It is undetermined because of "electrical noise" on the transmission line and the "encoder" (perhaps) not sharing the same signal ground. THAT undetermined and floating voltage drop could be high enough to damage the PLC. It could even be a negative potential.

Grounding one of the phase pairs might work, but I would rather recommend building a circuit to handle the signalling as it is suppose to be. The alternatives you mentioned are worth looking at.

Regards.