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Why input card 2 wire and 4 wire do not work
Created by: Jeevan Patil at: 1/12/2010 1:53 PM (11 Replies)
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| 1/12/2010 2:08 PM | |
Joined: 9/28/2005 Last visit: 12/10/2024 Posts: 2957 Rating:
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Hello, Did you make wiring correctly according to attached picture ? Furthermore, did you choose in HW config input as 4 wire transducer (also see attached) ? Attachmentscreen_001.zip (1313 Downloads) |
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Best regards, |
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| 1/17/2010 9:03 PM | |
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Posts: 51 Rating:
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have a look at the note at the foot of page 312 in theS7-300 Module data manual the 8 input channels of that module are in 4 groups (i.e 0 and 1 in a group, 2 and 3 in the next group etc....) the manual says: "Resistance measurement" is only available at one channel per group. The "2nd" channel of the group is used accordingly for current measuring mode (IC). The "1st" channel of the group returns the measured value. The "2nd" channel of the group is assigned the default overflow value "7FFFH." the way that reads to me is that you can only have up to 4 RTD inputs on that module. if you want to have 8 RTD inputs i would guess you'd need to change the module to something like a6ES7331-1KF02-0AB0 which has 8 inputs in 8 groups (see page 297 of the manual) |
| 1/19/2010 6:21 PM | |
Joined: 5/28/2008 Last visit: 1/2/2025 Posts: 4518 Rating:
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Hello Jeevan Patil, 6ES7331-7KF02-0AB0 SIMATIC S7-300, ANALOG INPUT SM 331, OPTICALLY ISOLATED, 8AI, RESOLUTION 9/12/14 BITS, U/I/THERMOCOUPLE/RESISTANCE INTERRUPT, DIAGNOSTICS; 1X20PIN REMOVE/INSERT W. BACKPLANE BUS The above module is AI 8 channels, but if you are using it for RTD mesaurments, it will be only 4 channels. This is important note you have to consider. Look on the attachment. In case you want to use the AI module for RTD, sellect in HW config as per the picture and do the wiring as mentioned and use addresses of channels 0, 2, 4, and 6 the other 4 channels will be un-available in this case. In my example, you will use PIW256, PIW260, PIW264 & PIW268. With best regards, Attachment7KF.zip (749 Downloads) |
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Ayman Elotaify |
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| 1/27/2010 11:27 PM | |
Joined: 7/2/2008 Last visit: 9/30/2024 Posts: 928 Rating:
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Hello Jeevan Patil, I see that things are mixed up. Darius considered that you used ''4-wire'' to describe a transducer/transmitter. tomearpand Ayman Elotaifythought you were referring to an RTD element connected with 4 wires. I guess you need help regarding 4-20 mA measurement. Correct me if I'm wrong.
It happens if you forget to rotate the measuring range module to the right position (asNavnaghas already said)and when your hardware configuration doesn't match actual configuration. You must make sure that everything is identical before you judge that both systems are the same. Now, you should, 1- Rotate the measuring range module to the correct position (Look at attachment). 2- Connect the signal wires (4-20mA) to a configured channel. 3- Supply your transmitter with 24VDC externally and make sure your device is active. 4- Put a multimeter in series between the device and the module and see if current varies according to transmitter measurement. 5- Make sure that your hardware configuration matchesyour connection(Look in Darius' first post). 6- Download your hardware configuration. 7- Checkthe analog valuein a your program or in VAT and look if it's varying or not. 8- If you still face problems, Open hardware configuration window, Station>Open ONLINE and click on module and check if it has something wrong. You can findmore infoin SIMATIC S7-300 SM331; AI 8x12 Bit Getting Started part 1: 4 -20mA. Best regards. H-H |
Last edited by: H-H at: 1/27/2010 11:34 PM |
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