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RS485

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Hi I have a problem, should I connect a PLC CJ1M with some PICs and to communicate as if it were a net in RS485, someone to already servant a similar configuration? THANKS

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Guest_max: Please register at MrPLC.com and join the MRPLC.com community Register at MrPLC.com What is PICS?

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I think he is refering to Programmable Integrated chips. kinda simple version of a 8080 chip. Ok I am not sure of the question.?? If you are asking if it is possible to communicate between a PIC and a CJM1 then the answer is yes as long as you set your pics up to comm using 422 or whatever the plc can do. I know that you can get the PIC to communicate using just about any of the main communication protocals out there it is even capable of devicenet. however I have never done it and dont have any examples. (sorry) Peace

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Well, It is important to know what PIC do you wantt to use. Generally PIC 16F877 series can be used easily for local automations, with the advantage of the USART inside, and plenty of I/O. However, PIC16F84 is not a good solution for automation, I don't know the reason for the high price of PIC16F84, because PIC16F628 is better, and cheaper than 16F84. With 16F877 or 16F628, you can communicate easily, however output pins are at TTL level, between 0 - 5 volts. You must have to use a level converter, preferably MAXIM IC's. If you want to use point to point mode (RS 232) you can use MAX 232. Or if you want to use RS 485, you have to use MAX 485 IC. And now the software side. If you think of RS 485 communications, the software in PIC must support the communication protocol. If you are programming your PIC with Microchip's assembler, it is difficult to write a communication program. I can offer you PIC C Compiler of HI-TECH, the lite version of this programmer is free, but limited on some specifications, for example with PIC C Lite, you can not work with floating numbers. But it is very easy to program with nearly ANSI C, Here are the keywords for google: MAX 232 MAX 485 PIC C Lite HI TECH May be you can find some circuit diagrams for RS 485 applications by PIC, I will also try to search my archive for these kind of applications. I remember one "Queue - Matic" application used in banks. I will try to find this sample circuit diagram. Best Regards.

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Can I do all with the RS232 integrated in the CJ1M or do I owe CJ1W-SCU21 or CJ1W-SCU41 to use an optional card? Does it serve a protocol particularly? Thanks so many

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just a note: you can request free samples of max232 and max485 at Maxim IC. and also free microchip PICs from Microchip.

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well you should be able to do start the communications from eather end. It should not matter. it depends on your application and which is easyer for you.

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The project that I should realize is to use a CPU omron CJ1M-11 and 10 PICs 16F628, what interests me and to communicate and to for instance exchange data among the PICs toward the CJ1M and in the contrary sense: light a value from the analogical input of the PIC etc. to a distance than at least 500 meters. Everything this is new for me I am sorry if I ask too questions but I don't know from whether to begin. Thanks for the attention.

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Is he asking for the protocol?

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Any program serves me where I can find some information or example of program? Thanks of the collaboration.

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The standard maxim RS 232 length is 50' but if data is async you can increase that distance to as much as 500' with a good grade of cable. So you will have to probably use some sort of wireless or signal boosting system. Omron CS1 and CJ1 Serial communication manual. Take a look at the manual for the communications of the plc this will give you a good idea on what you will need to do from the PLC side. there are also some examples in there. Edited by KinK

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I think RS 485 will be better. Use one RS 232 - RS 485 converter on PLC side. MAX 485 IC works with just 5V. I offer you PICC C Compiler, http://www.htsoft.com/downloads/demos.php you can easily program your 16F628. You can write your own communication protocol in both PLC and PIC, however, I offer you to use Hostlink protocol of OMRON. So, you will reduce the code in PLC. You can search OMRON HOST LINK MANUAL in forums. I have attached datasheet of MAX 485. Best Regards. MAX1487_MAX491.pdf

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