Serial Communication with Twido

jnordhag · Feb 12, 2006

I am a Mechanical Engineering student working on a Senior Design project that is over my head, please help.

I have a Twido PLC which needs to communicate with the controller from a light-curtain sensor. The controller will output either an RS232 or RS485 signal in ASCII format, and the PLC has an RS485 port. Is either of these easier or preferable to work with from the PLC end of things? What do I need to do in the PLC programming to receive the signal from the light-curtain controller? I don't know how to get this into my ladder program, or what to do with it once it is there. Any help on this topic would be very much appreciated.

Thanks,
Jon

CaseyK · Feb 13, 2006

Check your light curtain for a NO or NC (normally open or normally closed) contact, that can be wired directly into one of the Twido inputs.

Serial communication, if in fact it is posible, will probably be difficult, at best.

regards.....kc

jjvijay · Feb 13, 2006

WHAT FOR U ARE USING SERIAL COMM BETWEEN CONTROLER WITH plc

jnordhag · Feb 13, 2006

The light-curtain is made up of 128 separate beams. The controller can output exactly which beams are broken and which are not, but it is in the form of an ASCII serial signal. We need this information as an input to the PLC.

Jon

10baseT · Feb 13, 2006

If you do that (serial coms) , by definition , then you won't be using the light barrier as part of a safety dependent process .

These comms are not generally used in the way you imply -

jnordhag · Feb 15, 2006

The light-curtain is used to detect width and position of an object; it is not being used as a safety device like most are. From my understanding, the serial port is normally used to connect and communicate with slave PLCs. I thought that it might be possible to set up the light-curtain controller as a slave to the Twido PLC, but I don't know if this will work, or how to do this. It is not a common on/off input; it is a serial signal which I haven't found much information on. I have read some about saving the signal into the memory in the PLC and then calling it out in the ladder program. Is this a possible approach? I really don't have a understanding of how this connection works and am searching for any help possible.

Thanks for the replies,

Jon

Serial Communication with Twido

jnordhag

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CaseyK

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jjvijay

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jnordhag

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10baseT

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jnordhag

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