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Communication module

Created by: GaJEnDrA D S at: 5/17/2016 5:39 AM (21 Replies)

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5/17/2016 2:29 PM	Rate (0)
Jeff Casagrande Posts: 1529 Rating: (203)	Please google 2 wire and 4 wire RS485. You will find that you will be grounding the - signals.
Jeff Casagrande Posts: 1529 Rating: (203)
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This contribution was helpful to 2 thankful Users William_B GaJEnDrA D S

5/17/2016 4:35 PM	Rate (2)
William_B Posts: 5225 Rating: (1197)	Hi. I think it is important for this case to know what the S7-1200's communication partner requires. Not only in the hardware link, but also the protocol. Modbus RTU for example is defined for RS232 and RS485. Recently I had to design a network for the S7-1200 linking to Yaskawa V1000 variable speed drives. The drives are capable of linking via RS422 or RS485 via x4 pins. When linking RS485, the pins are paired to give two signals. See the example below.. My opinion: Anything added to this will be pure speculation without having information on what devices need to communicate and which protocol is used. Greetings.
William_B Posts: 5225 Rating: (1197)
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This contribution was helpful to 1 thankful Users Duris_I

5/19/2016 10:26 AM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 11/1/2023 Posts: 324 Rating: (19)	Hi i want to send this data to my rs 485 counter. DA1R# -- ASCII protocol. Module : 6ES7241-1CH30-0XB0* PLC 1214C DC/DC/RLY Half duplex Pls tell me which instruction to be used? there are 2 PtP instructions ! Buffer parameter is array of char. is that correct? Attachment Buffer.PNG (466 Downloads)
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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5/19/2016 10:27 AM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 11/1/2023 Posts: 324 Rating: (19)	Instructions. Attachment instruction.PNG (517 Downloads)
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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5/19/2016 12:55 PM	Rate (1)
Duris_I Diamond Member Joined: 4/28/2015 Last visit: 12/25/2024 Posts: 10704 Rating: (831)	Hello, I think looks ok, but test also Send instruction bit DONE for true and then set RECV instruction EN_R to true, simply if your send is OK (DONE=true), then set SEND REQ to false (you need now receive) and set EN_R in RCV instruction to true. Now you will receive data. After test NDR = true (data received) you set that EN_R to false (you received data, now you can send) and via some condition again set that REQ for SEND. If you look now to your Picture, you have still true for SEND and you cant RECV, you must know when change send/receive. Try this conditions and give info.
	With best regards... Ivan Duris Flight: OMICO
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5/19/2016 1:18 PM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 11/1/2023 Posts: 324 Rating: (19)	Actually i only want to send data first which is not happening. Recieve is simply put. 1) My doubt is i dont connect any device to rs 485 module. And execute send ptp instruction. Will txd led on c.module blink? Coz then only i can expect data to be sent to counter. . 2) I still dont have clarity between these two send instructions .
	Last edited by: GaJEnDrA D S at: 5/19/2016 1:24:14 PM "Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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5/19/2016 1:19 PM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 11/1/2023 Posts: 324 Rating: (19)	To add more info m getting status w#7000
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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5/19/2016 1:55 PM	Rate (1)
Duris_I Diamond Member Joined: 4/28/2015 Last visit: 12/25/2024 Posts: 10704 Rating: (831)	Your 2 SEND instructions are independent, look, they have own EN memory, why you're using 2 SEND instructions? Yes, if you set on SEND instruction REQ to true, LED TX must blink, it doesn't matter if you have some device connected, this is CM side. As I post before, prepare simple bool condition if your DONE bit will be true after triger of REQ, then you'll be sure that data was sended.
	With best regards... Ivan Duris Flight: OMICO
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5/19/2016 2:09 PM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 11/1/2023 Posts: 324 Rating: (19)	M not using both at a time. M switching between them to make sure which instruction suits my application. Tats the reason m asking Wat is the difference between them.
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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5/19/2016 6:52 PM	Rate (0)
GaJEnDrA D S Bronze Member Joined: 8/9/2011 Last visit: 11/1/2023 Posts: 324 Rating: (19)	Hi above instruction working checked module without device why not the below one? There is no proper description neither in manual nor in help of TIA where you can differentiate the two instructions. refer below picture tag_3 is 10 hz clock . there is no 0000 value in status table for instruction that is executing but its getting that value (output of last move) which is a part of in other instruction . some bug i think. Attachment Capture.PNG (412 Downloads)
	"Any intelligent fool can make things bigger, more complex. It takes a touch of genius -- and a lot of courage -- to move in the opposite direction.":):)
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