# Ignition communication with siemens S7-400 PLC failed **URL:** \ **Category:** Ignition\ **Created:** [March 5, 2016, 9:13am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318 "2016-03-05T09:13:20Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![joshi.pradnya06](https://avatars.discourse-cdn.com/v4/letter/j/e68b1a/32.png) [@joshi.pradnya06](https://forum.inductiveautomation.com/u/joshi.pradnya06)\ **Post date:** [March 5, 2016, 9:13am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/1 "2016-03-05T09:13:20Z")
Hello, I am trying to communicate IGNITION 7.3.7 with Siemens S7-400 PLC. But PLC remains disconnected. PLC gets pinged though.Ignition Error logs say: the connection is refused. Please advice on how to get rid of this. Is there any specific setting in Ignition for S7-400 plc communication?If yes please specify. Thanks, Pradnya ---
**Author:** ![zxcslo](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/zxcslo/32/61610_2.png) [@zxcslo](https://forum.inductiveautomation.com/u/zxcslo)\ **Post date:** [March 6, 2016, 8:50am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/2 "2016-03-06T08:50:01Z")
There isn't any 'specific' setting.... The only setting, which matter for connecting to S7-400 PLC is 'CPU Slot Number'. With S7-400 is either 2 or 3, depends on which power supply you have on S7-400: - if you have narrow PS, then your PLC is in slot 2 - if you have wide PS, then your PLC is in slot 3 [attachment=0]S7\_414PLC - Ignition Gateway.png[/attachment] With S7-300 slot is always 2. ---
**Author:** ![joshi.pradnya06](https://avatars.discourse-cdn.com/v4/letter/j/e68b1a/32.png) [@joshi.pradnya06](https://forum.inductiveautomation.com/u/joshi.pradnya06)\ **Post date:** [March 7, 2016, 8:33am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/3 "2016-03-07T08:33:00Z")
Ok I will check. ---
**Author:** ![Tobias](https://avatars.discourse-cdn.com/v4/letter/t/c67d28/32.png) [@Tobias](https://forum.inductiveautomation.com/u/Tobias)\ **Post date:** [January 31, 2017, 9:18am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/4 "2017-01-31T09:18:22Z")
Hi, is there a solution to the Problem yet ? I have the same Problem, CPU-Slot number is set correctly. i have a CP443-1 (6GK7 443-1EX10-0XE0) and Ignition V 7.7.4 ---
**Author:** ![maripierdo](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/maripierdo/32/16478_2.png) [@maripierdo](https://forum.inductiveautomation.com/u/maripierdo)\ **Post date:** [October 19, 2017, 8:25pm UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/5 "2017-10-19T20:25:44Z")
Hi! I have thesame problem. Could anyone was able to solve the problem with S7400 plc? Thanks ---
**Author:** ![Sparkblender](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/sparkblender/32/4373_2.png) [@Sparkblender](https://forum.inductiveautomation.com/u/Sparkblender)\ **Post date:** [November 17, 2017, 8:27pm UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/6 "2017-11-17T20:27:51Z")
I’m having the same issues. I’m running Ignition 7.9.4 on a Windows Server 20016 machine, from which we can ping our SIMATIC S7-400 PLCs (each connected via CP 443-1). Nevertheless, we don’t seem to be able to connect to them. Status is repetitively switching between Disconnecting and Connecting states. We verified all parameters, and they all seem ok, including the CPU slot. Please help! Thanks. ---
**Author:** ![zxcslo](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/zxcslo/32/61610_2.png) [@zxcslo](https://forum.inductiveautomation.com/u/zxcslo)\ **Post date:** [November 18, 2017, 8:09am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/7 "2017-11-18T08:09:42Z")
Communication with all Siemens PLC’s is over port 102 by default. So check your firewall in windows and let the port 102 through… ---
**Author:** ![Sparkblender](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/sparkblender/32/4373_2.png) [@Sparkblender](https://forum.inductiveautomation.com/u/Sparkblender)\ **Post date:** [November 30, 2017, 1:59am UTC](https://forum.inductiveautomation.com/t/ignition-communication-with-siemens-s7-400-plc-failed/11318/8 "2017-11-30T01:59:07Z")
We finally got to the bottom of the issue. Here’s the summary: In order to test the connection, we tried running the following command line from the Ignition Server: telnet IP 102 where IP is the PLC’s IP address and 102 is the standard port used to communicate with the SIMATIC S7-400 PLCs. If an error is returned, then this means that the Ignition server is not able to communicate with that IP address via port 102. We had to contact the Network Administrator, who opened the communications via port 102 for us, after which all started working. It’s interesting to note, that prior to that, there were no messages being displayed under Status-\>Diagnostics-\>Logs. Only after the networking issue was resolved, we starting seeing messages in the Logs section. Port 102 is the default to communicate with SIMATIC S7-400 PLCs. These ports are fixed, and there is no way to configure them otherwise. For more information, please refer to the following link: [https://support.industry.siemens.com/cs/document/8970169/which-ports-are-used-by-the-various-services-for-data-transfer-via-tcp-and-udp-and-what-should-you-watch-out-for-when-using-routers-and-firewalls-?dti=0&lc=en-WW](https://support.industry.siemens.com/cs/document/8970169/which-ports-are-used-by-the-various-services-for-data-transfer-via-tcp-and-udp-and-what-should-you-watch-out-for-when-using-routers-and-firewalls-?dti=0&lc=en-WW) Thanks for helping.