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FM355 and Pt100

Created by: andrewF at: 7/16/2008 9:58 AM (7 Replies)

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7/16/2008 9:58 AM	Rate (0)
andrewF Posts: 87 Rating: (1)	How I can connect atemperature resistor (6SC8391-0AA0 ) to FM355 with 4-wire? If this PT100 hawe only 2 wire (may be I can sold dedicated 2-wire)?
andrewF Posts: 87 Rating: (1)
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7/18/2008 5:14 PM	Rate (0)
Denilson Pegaia Platinum Member Joined: 9/23/2005 Last visit: 11/11/2024 Posts: 4351 Rating: (1452)	Hi, if you use a 2 wire sensor as 4 wire, you will loose some precision in the measurement. However, if you don't have any other possibility, you can make a jump between the input bornes (for exemple, 2 with 4 and 3 with 5 for chamel 0)
	Denilson Pegaia Siemens Industry Sector Technical Support
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7/21/2008 8:42 AM	Rate (0)
andrewF Posts: 87 Rating: (1)	Of cause I understand this! But I want have maximum precission, though for measerment by termocouple precission approximately few decimal digit is not essentially, but 4-wire is scribed in MANUAL!
andrewF Posts: 87 Rating: (1)
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7/21/2008 9:23 AM	Rate (0)
Aret Posts: 2348 Rating: (264)	First of all i'm not elecrician, so i may be wrong :^) All Pt100 i've seen had 3 wires. To connect it for 4 wire scheme you need: 1. connect4wirestoFM355accordingmanual 2. connect BOTH pin 2 wire and pin4 wire at PT 100 side to +wire 3. connectpin3wireandpin5wiretat PT100 side tocorresponding-wires Maybe i got your questionwrong-i'veusedFM355Stepmanual. Couldn'tfindmanualforPT100(bythewayit'sNOTthermocouple)-canyouprovidealinktoit?
Aret Posts: 2348 Rating: (264)
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7/21/2008 12:11 PM	Rate (0)
andrewF Posts: 87 Rating: (1)	1. Pt100 used for compensating cold junction of connected termocouple. 2. 4-wires connecting used for compensating resistance of measurement wires. 3. First 2 wires used for connecting current source(Ic+, Ic-), other 2 wires (C+, C-)used for measurement voltage. In manual recommended 4-wires connecting, but I get ordered PT100 and he have 2 wires internal mounted? Why only 2 wires if in manual write "connecting 4 wires"?
andrewF Posts: 87 Rating: (1)
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7/21/2008 12:21 PM	Rate (0)
andrewF Posts: 87 Rating: (1)	This circuit..... Attachment pt100.jpg (277 Downloads)
andrewF Posts: 87 Rating: (1)
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7/21/2008 1:16 PM	Rate (0)
Aret Posts: 2348 Rating: (264)	1. Pt100 used for compensating cold junction of connected termocouple. If this is true, then you can configure 2 wire scheme because: 2. 4-wires connecting used for compensating resistance of measurement wires. And junction point is located in you PLC's room - soresistance of measurement wires is very small 3. First 2 wires used for connecting current source(Ic+, Ic-), other 2 wires (C+, C-) used for measurement voltage. In manual recommended 4-wires connecting, but I get ordered PT100 and he have 2 wires internal mounted? Why only 2 wires if in manual write "connecting 4 wires"? As i wrotebeforei'mnotquitesure,butiwouldtrytoconnect Ic+andV+toonesideofPT100, Ic-andV-tootherside
Aret Posts: 2348 Rating: (264)	Last edited by: Aret at: 7/21/2008 1:17 PM
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7/21/2008 3:00 PM	Rate (0)
andrewF Posts: 87 Rating: (1)	Ok! I would try do it !!!
andrewF Posts: 87 Rating: (1)
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