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S7-1200 CM12XX extension cable?

Created by: AlesPoljakNOJP at: 5/24/2021 1:12 PM (9 Replies)

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5/24/2021 1:12 PM	Rate (0)
AlesPoljakNOJP Experienced Member Joined: 8/25/2014 Last visit: 4/19/2024 Posts: 133 Rating: (1)	Hello. So, I have ran out of room in one of the control cabinets. I need to install a communication module to the S7-1200 PLC. Is there a cable that I can use to connect the PLC and the CM module that would be located on another DIN rail where there is space left? Would this cable work? Extension cable 2-tier setup for SM 12XX -6ES7290-6AA30-0XA0 Cheers. Aleix

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5/24/2021 1:35 PM	Rate (0)
Mr.V Silver Member Joined: 6/19/2019 Last visit: 10/29/2024 Posts: 705 Rating: (76)	Hello, I think it will work.

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5/24/2021 1:40 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 11/7/2024 Posts: 12293 Rating: (2691)	Hello Poljo; The S7-1200 expansion cable you are pointing to is designed to connect a CPU to a SM (DI, DO, AI, AO module) at a distance of 2 m, but not to a CM See te S7-1200 Programmable Controller manual for details on the insstallation of this cable: https://support.industry.siemens.com/cs/ww/en/view/109797241/139335322123 However, since the CM can be installed on the left of the CPU O_Einstein has a suggestion in this discussion that could help you, refer to his last reply: https://support.industry.siemens.com/tf//ww/en/posts/expansion-cable-for-cm-with-cpu1200/205235/?page=0&pageSize=10 Hope this helps, Daniel Chartier: Attachment S7-1200 IO expansion cable.jpg (513 Downloads)
	Last edited by: dchartier at: 05/24/2021 13:42:41
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5/24/2021 2:10 PM	Rate (0)
Mr.V Silver Member Joined: 6/19/2019 Last visit: 10/29/2024 Posts: 705 Rating: (76)	Then Siemens do strange things, if the module pins are same like other module then why not can use extension cable, theoricaly it must work because or connect directly or via cable i think it must work.

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5/24/2021 2:21 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/6/2024 Posts: 15385 Rating: (2443)	The extension cable is only for modules that can be installed to the right of the PLC. Modules which require being placed to the left of the plc, like COMM modules (rs232/rs422/rs485/profibus for example), they must be placed directly to the left of the plc. I have not heard of any extension cable for the left side of the plc. If it exists, it will be in the s7-1200 system manual, as are the instructions for using the s7-1200 extension cable. Mr.V Then Siemens do strange things, if the module pins are same like other module then why not can use extension cable, theoricaly it must work because or connect directly or via cable i think it must work.
	science guy
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5/24/2021 2:30 PM	Rate (0)
Mr.V Silver Member Joined: 6/19/2019 Last visit: 10/29/2024 Posts: 705 Rating: (76)	But did someone try this one variant from left side? 0_Einstein The extension cable is only for modules that can be installed to the right of the PLC. Modules which require being placed to the left of the plc, like COMM modules (rs232/rs422/rs485/profibus for example), they must be placed directly to the left of the plc. I have not heard of any extension cable for the left side of the plc. If it exists, it will be in the s7-1200 system manual, as are the instructions for using the s7-1200 extension cable. Mr.V Then Siemens do strange things, if the module pins are same like other module then why not can use extension cable, theoricaly it must work because or connect directly or via cable i think it must work.

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5/24/2021 2:47 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 11/7/2024 Posts: 12293 Rating: (2691)	Hello Mr. V; I haven't tried this variant myself. But just to add a hint of understanding of why there should be a difference between the connections to SMs and CMs to the CPU, look at the following (old) discussion: https://support.industry.siemens.com/tf//ww/en/posts/difference-between-c-bus-k-bus-and-p-bus/57678/?page=0&pageSize=10 In the S7-300 and s7-400 families, connections on the backplane connectors between the CPUs and the modules on the rack were distinguished between 2 different connections: P-bus and K-bus, and the distinction was extended to the expanded rack IMs: for example, with a IM 365, there was no support on rack 1 (rack 0 being the one where the CPU was located) for the K-bus, so no communication module or function module could be located on it. Only the P-bus was connected to rack 1, so it could only handle SMs . See the attached screenshot, taken from th S7-300 Module Data manual. There is probably something similar in the design of the S7-1200 expansion cable that allows it to connect only with SMs... Hope this helps, Daniel Chartier Attachment S7-300 expansion rack IMs.jpg (384 Downloads)
	Last edited by: dchartier at: 05/24/2021 15:01:23
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This contribution was helpful to 1 thankful Users Mr.V

5/24/2021 3:02 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/6/2024 Posts: 15385 Rating: (2443)	No need to try. Take a look at any s7-1200 that accepts modules to left and right. Or, you can stare at images online and see they are not going to accept that extension cable on the left. I can wish all I want for the old style USB cable to flip over and plug in, but even though it looks like it might, it simply refuses to insert and function. If you do manage to force the plug to go in, the odds of anything other than a ruined usb port and damaged cable are 0. USB-C, that's like s7-1200's of the 22nd century. Mr.V But did someone try this one variant from left side? 0_Einstein The extension cable is only for modules that can be installed to the right of the PLC. Modules which require being placed to the left of the plc, like COMM modules (rs232/rs422/rs485/profibus for example), they must be placed directly to the left of the plc. I have not heard of any extension cable for the left side of the plc. If it exists, it will be in the s7-1200 system manual, as are the instructions for using the s7-1200 extension cable. Mr.V Then Siemens do strange things, if the module pins are same like other module then why not can use extension cable, theoricaly it must work because or connect directly or via cable i think it must work.
	science guy
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This contribution was helpful to 1 thankful Users Mr.V

5/25/2021 9:15 AM	Rate (0)
AlesPoljakNOJP Experienced Member Joined: 8/25/2014 Last visit: 4/19/2024 Posts: 133 Rating: (1)	Hello guys. Thanks for the input. I need to mount a CP1243-1 comm module to the PLC. So based on your comments my best way is to move a I/O module to a different din rail with the extension cable to make room for the CP module... This sucks because this is a lot of work. I will need to rewire the I/O module that I will move. Thanks. Cheers Aleix.

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5/25/2021 4:59 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 11/6/2024 Posts: 15385 Rating: (2443)	I completely understand that. I work with someone that used to consistently undersized enclosures, used shallow wire ducting, and ended up having to mount stuff in very strange configurations, like din-rail with terminals and active components on the sides and sometimes enclosure door just to fit everything. Now, he finally understands why 30% extra space is not really extra (at least in our line of work where change is a constant rather than sporadic thing). I personally worked on a project I felt like I had right-sized it. After many engineering changes and new sensors and 6 more enclosure penetrations (the enclosure had been customized with pre-done holes.....), everything fits, with room for maybe a couple small terminals, and that's about it. One new sensor's amplifier module was as large as the s7-1211 PLC. I also for deep wire ducting. The cost difference between shallow and deep is negligible. The ease of routing wiring is most appreciated when things change, which is often.. Poljo77 Hello guys. Thanks for the input. I need to mount a CP1243-1 comm module to the PLC. So based on your comments my best way is to move a I/O module to a different din rail with the extension cable to make room for the CP module... This sucks because this is a lot of work. I will need to rewire the I/O module that I will move. Thanks. Cheers Aleix.
	science guy
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This contribution was helpful to 2 thankful Users qwazee Hati

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