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How to communicate s7-1200 with Danfoss fc-301

Created by: loquiyo at: 6/14/2012 5:55 PM (6 Replies)

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6/14/2012 5:55 PM	Rate (0)
loquiyo Posts: 3 Rating: (0)	Hi all. first of all I am new to this subject, I have a plc s7-1200 and CM-1241 module RS 485 and i need to communicate with a drive Danfoss FC-301 via RS 485. The control frame is as follows: a start character STX = 02 hex, followed by the character in length LGE, ADR, characters of the message and finally the BBC (checksum). I checked the pins 3 and 8 CM module 1241 rs 485 and I noticed that the character does not send STX as standard protocol, the checksum either. my question is if I am correct? or I will have a configuration error, or if the data array should I put the STX and the checksum to make and add to the arrangement that I sent to the block SEND_PTP. or if the module CM 1241 rs 485 automatically sends the STX and BCC,and how to set it up? thanks for the attention
loquiyo Posts: 3 Rating: (0)
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6/14/2012 6:45 PM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 3/17/2025 Posts: 15724 Rating: (2488)	loquiyo Hi all. first of all I am new to this subject, I have a plc s7-1200 and CM-1241 module RS 485 and i need to communicate with a drive Danfoss FC-301 via RS 485. The control frame is as follows: a start character STX = 02 hex, followed by the character in length LGE, ADR, characters of the message and finally the BBC (checksum). I checked the pins 3 and 8 CM module 1241 rs 485 and I noticed that the character does not send STX as standard protocol, the checksum either. my question is if I am correct? or I will have a configuration error, or if the data array should I put the STX and the checksum to make and add to the arrangement that I sent to the block SEND_PTP. or if the module CM 1241 rs 485 automatically sends the STX and BCC,and how to set it up? thanks for the attention Have you succeeded in building your library of FBs/FCs for parsing the received data and building up responses for sending? Have you succeeded in configuring the RS485 module to accept a packet from the drive? To me, that's the most important piece. The module does absolutely nothing for you automatically. You have control over the message packet layout in that you can set it up to being packet receipt upon sensing 16#02, but for sending, you pretty much set up the packet as needed, then push it into the send buffer, and trigger the send, then monitor for error or done. Note that the error/done bits are only guaranteed to be on for one scan, so you will need to latch onto it if you are tracking up or queuing data. What have you done so far? Screenshots would be very helpful. Look in the search box or do a google search RS485 or RS-485 or CM-1241 or CM1241 and s7-1200. There are FAQs as well. The HEX, it is actual hex, or is it ASCII hex? There is helpful blocks to help with that if required to convert between them. To make it human-readable, you can push your packet to a HEX->ASCII HEX conversion so you can see the data more easily in online debuggin, watch table or on an HMI.
	science guy
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6/15/2012 1:36 AM	Rate (0)
loquiyo Posts: 3 Rating: (0)	hello, thanks for your response, I have created an array of type byte size 6. unfortunately the drive firmware fc 300 has a 4.2 version which does not support Modbus RTU. FC protocol is supported, so the comuniacion point to point. in the FC protocol description says send STX, LEG, ADR, DATA and BCC. where LGE = number of data bytes plus two (ADR and BCC). then I have send [0] = 16 # 02 ... STX send [1] = 16 # 04 ..... 2 bytes + 2 (STX + ADR) send [2] = 16 # 01 .. Drive address send [3] = data send [4] = data send [5] =???? = BCC .... too? STX too? I apologize if I have written the same, and following your advice'll set to receive messages from the slave (drive) and to capture the frames with the oscilloscope. Thank you.
loquiyo Posts: 3 Rating: (0)
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6/15/2012 4:01 AM	Rate (0)
0_Einstein Diamond Member Joined: 7/7/2010 Last visit: 3/17/2025 Posts: 15724 Rating: (2488)	loquiyo hello, thanks for your response, I have created an array of type byte size 6. unfortunately the drive firmware fc 300 has a 4.2 version which does not support Modbus RTU. FC protocol is supported, so the comuniacion point to point. in the FC protocol description says send STX, LEG, ADR, DATA and BCC. where LGE = number of data bytes plus two (ADR and BCC). then I have send [0] = 16 # 02 ... STX send [1] = 16 # 04 ..... 2 bytes + 2 (STX + ADR) send [2] = 16 # 01 .. Drive address send [3] = data send [4] = data send [5] =???? = BCC .... too? STX too? I apologize if I have written the same, and following your advice'll set to receive messages from the slave (drive) and to capture the frames with the oscilloscope. Thank you. From another web site: (BCC) This character is transmitted by the instrument at the end of its message to be used by the supervisory computer for data verification purposes. The BCC is a longitudinal redundancy BLock Check Character generated by taking the exclusive-OR of all the characters transmitted after the STX character up to and including the ETX character The message receiving is often the best place to start as you may learn something about the drive communications protocol that may save you considerable time. However, it could not hurt to try sending a test message using the watch system and verify the drive is receiving the proper values into the correct locations.
	science guy
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6/24/2012 4:44 PM	Rate (0)
loquiyo Posts: 3 Rating: (0)	Hi! thanks again, as you said the 1241 cm module does nothing for me, at least in the way point to point, right now I can already send and receive data frames. STX, LGE, ADR, (DATA), BCC also
loquiyo Posts: 3 Rating: (0)
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3/9/2016 2:33 PM	Rate (0)
LynG3 Posts: 1 Rating: (0)	Hey guys I know this is a long shot but could you show me what specifically you are sending to the FC301, im having trouble with getting it to respond over RS485.
LynG3 Posts: 1 Rating: (0)
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7/10/2017 1:52 PM	Rate (0)
Jen_Moderator Diamond Member Joined: 6/19/2017 Last visit: 9/6/2024 Posts: 8175 Rating: (174)	New question published by Jchip is split to a separate thread with the subject S7-1200 with Danfoss fc-301: How to send and receive data?. Best regards Jen_Moderator

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