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mr_shadow

ENCODER TO PLC DIGITAL INPUT CONNECTION

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D05E6C2C1101.pdfpnp_enc_plc_pnp_input_connection_.pdfHi all, I have some problems with the connection of "E6C2-C6WZ NPN open collector output " encoder ,as my pulse frequency is low i am trying to connect PHASE A , PHASE B AND Z of this encoder to directly a NPN digital input unit , but as i am not good at electronics i couldn't do it , i found something in the manual of the encoder, if i do the same connection that is defined for CQM1H-CPU43 for other NPN type PLC DIGITAL INPUT UNIT does it work or not? can anybody help me with this problem?

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I am unsure if it would work or not, you will need to see what is the min pulse time allowed for the DI, how low a frequency are you talking about, this will def be an issue. Most applications that use encoders use a dedicated HSC input specifically for this reason. I don't have the ability just now to do the math, but instinct says maybe not.

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Although you can just use the internal pull ups to the inputs to make the NPN encoder drive the PNP inputs on the PLC I would use 3 opto couplers to separate the Encoder from the PLC and provide the 'inverter/buffer' you need. http://rswww.com/cgi-bin/bv/rswww/searchBr...heID=uknetscape These and other similar 'buffer/optocoupler' terminals from wiedmuller etc would allow you to hook up the Encoder with little effort and no risk of killing it! In the case of the Entrelec/Abb terminal shown: connect Encoder output A to terminal A1, connect term A2 to your +V supply to the encoder (these can be inverted with no problems!), connect output buffer term + to your PLC Inputs +V Common rail and connect the - output of the buffer term to your PLC's digital input terminal for Enc A (IN04). Do the same for EncB(IN05) & Z(IN06). These are the connections for the HSC, You would be best off using one of the 'high speed' counter' channels as they have the quadrature and filter functions in the PLC setup pages - you can select what rate to set the counter at and if you want 4x pulses going in the counter. If the pulses are mega slow you could just hook them to a standard high speed input and call an interupt that increments your counter - but without using a HSC you always run the risk of losing a few pulses - you might think the pulses are slow but what happens if the machine is stopped with the encoder just on/off a line 'jittering', without using 4x quadrature and HSC your low speed counter would clock up 'phantom pulses' that the HSC would filter or count up/down correctly. This is a 'belt and braces' system, the LEDs on the isolator terminal shows you the encoder is working, you could have different voltages on the Encoder and PLC (maybe have to use slightly different buffer term), you run no risk of killing the encoder output as it only drives an LED that has the proper pull up / down value, the input to the PLC is buffered giving the PLC protection from the nasties in the outside world. And it looks neater than resistors soldered all over the place. I use these for many Encoder / Sensor inputs and use the 1&2Amp versions on Valve outputs from the PLC. Edited by Mark The Spark

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Just to clarify, there is no CQM1H-CPU43, there is a CQM1-CPU43 which was the high speed pulse input/output processor. There are two 15 pin D sub connectors on the front of the unit. Is this what you have? Where are you trying to connect the encoder. That encoder part number is for an NPN open collector output. It will wire up to the D sub connectors. You may or may not be able to make it work by wiring to an input module depending on the pulse speed. However, the built in DC inputs on the cpu, I think it is 4, 5, and 6 were designed to handle "high" speed encoder input. I would recommend that you get a copy of the W226 manual. Available here on Mr PLC.com: W226 CQM1 manual at Mr.PLC.com Hope this will help Okay, lets try this again. In re-reading your post, what are you trying to connect the encoder to? What plc, brand, model number, etc? What problems are you having with the current connections that you have? Any information that you can supply would be helpful. Edited by gtsuport

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