Posted 1 Aug 2012 Hello, We have to configure a Q series PLC that needs to comunicate with: - 2 or 3 Modbus Slave devices (RS485) - 3 proprietary protocol devices (each use 1 serial port for communication) Which serial port module should I use: QJ71C24N or QJ71MB91. The QJ71MB91 support native modbus master/slave protocol but I didn't read nothing about supporting user protocol (like RS function in FX series). On the other hand the QJ71C24N supports a variety of methods for communication using user protocols, but it looks like it doesn't support Modbus. Are there any function blocks that I could use for implementing modbus protocol on QJ71C24N, or I should use one QJ71MB91 and one or more QJ71C24N modules. I have choose the Q03UDE CPU with Ethernet interface. Does the Ethernet interface, which is equipped with, support modbus TCP slave protocol? I'm a beginner in Q series PLC. Thank you. Share this post Link to post Share on other sites
Posted 1 Aug 2012 (edited) Modbus TCP protocol is supported by QJ71MT91 module only. Edited 1 Aug 2012 by Inntele Share this post Link to post Share on other sites
Posted 1 Aug 2012 Agreed, however depending if you want RS232 or RS485 you can choose QJ71C24N-R2 or QJ71C24N-R4. That way you can use one card for two peripheral devices... Share this post Link to post Share on other sites
Posted 1 Aug 2012 Modbus TCP protocol is supported by QJ71MT91 module only and the PLC of a series of QnU with a built-in Ethernet. Share this post Link to post Share on other sites
Posted 2 Aug 2012 Hello, I have found the library for the modbus tcp (client/server) for built-in Ethernet (article id on beijer site: DSSE-8QDHC7(GX Works) or DSSE-8RHGF5(GX IEC)), but i didn't found the modbus library for QJ71C24N. I will use the built-in Ethernet with modbus tcp for local SCADA, and I think the speed is ok (article id: DSSE-8RJBX2). I think I will use the QJ71MB91 anyway, but I just want to see if it is possible to use modbus protocol with QJ71C24N module. Thank you. Share this post Link to post Share on other sites
Posted 6 Aug 2012 The QJ71C24N supports several built-in protocols, which can be selected and configured with GX Configurator-SC or the built-in tools in GX Works2. Modbus is one of them. Share this post Link to post Share on other sites
Posted 6 Aug 2012 Dear Crossbow, How long the QJ71C24N supports Modbus as pre-defined and where it's written? Share this post Link to post Share on other sites
Posted 6 Aug 2012 You're not right.For this unit, there is no configurator modbus. Share this post Link to post Share on other sites
Posted 8 Aug 2012 I am right. I just fired up GX Configurator-SC, selected the predefined protocol function, selected Schneider Electric, and then Modbus. Share this post Link to post Share on other sites
Posted 9 Aug 2012 GX Configurator-SC works with GX Developer.What software uses WKLa we do not know. Share this post Link to post Share on other sites
Posted 17 Oct 2012 (edited) I am using GX Works 1.77, but I can't seem to find the modbus protocol. The modbus option is available only when using GX Configurator-SC with GX Developer? Anyone knows if modbus can be selected in GX Works? Thank you. Edited 23 Oct 2012 by WKla Share this post Link to post Share on other sites
Posted 12 Nov 2012 Anybody has some information? Should I install GX Configurator-SC or is it included in GX Works? Share this post Link to post Share on other sites
Posted 12 Nov 2012 sh080921engj C:\Program Files\MELSOFT\GPPW2 Share this post Link to post Share on other sites
Posted 12 Nov 2012 GX Configurator-SC is not needed when using GX Works2. The replacement is built in. Share this post Link to post Share on other sites
Posted 13 Nov 2012 Thanks to KAZAH and Crossbow, I have found the aplication and the settings for modbus communication for QJ71C24N. It looks very simple to use, but I will bother you with other questions. Share this post Link to post Share on other sites
Posted 13 Dec 2012 Hello again, I have a problem with Modbus TCP/IP using built in Ethernet (article id on beijer site: DSSE-8QDHC7(GX Works)). It looks like I can only read M bits. I want to read L bits (that are latched). I have a lot of latch bits (L) that should be read and write from SCADA. If you have any suggestions, please post it fast, it is urgent! I also have an QJ71E71-100 unused module on my system. Thank you! Share this post Link to post Share on other sites
Posted 13 Dec 2012 You cannot use the E71 card. They don't allow port numbers to be used below 1024, and ModbusTCP uses 502. Share this post Link to post Share on other sites
Posted 21 Jan 2013 Regarding the settings for QJ71C24N-R4. I have accessed "tool/intellingent function module tool/serial communication module/predefined protocol support function" from GX Works menu. Added Modbus Protocol and then configured the registers for communication (see attached pictures) . I wrote the configuration to the PLC and performed Reset, Run-Stop-Run, but the communication card doesn't sent anything (the Rx, Tx leds not flicking). Any idea what am I doing wrong? Thank you. Share this post Link to post Share on other sites
Posted 22 Jan 2013 How does your cable look like? It should be: 2-3 3-2 5-5 Latches on C24 side (and probably on the slave side too): 1-4-6 7-8 Alternatively a crossover cable can be used IF your slave device supports hardware handshakes. Share this post Link to post Share on other sites
Posted 23 Jan 2013 I am using QJ71C24N-R4 (2x RS485/RS422). I didn't connect the cables to the slave device yet. Share this post Link to post Share on other sites
Posted 25 Jan 2013 When using the Intelligent tool, did you remember to download the configuration?? Share this post Link to post Share on other sites
Posted 13 Feb 2013 Because I was in doubt with that I've checked the configurations with Module Read/Write /"Module Verification..." from intelligent tool menu. The configurations are identical. I don't know how to set on which port the predefined protocol is active, maybe I've made something wrong. Thank you. Share this post Link to post Share on other sites
Posted 15 Feb 2013 Did you check the "Prohibit echo"? This ensures that you don't receive your own telegrams. I see that you are using channel 2, correct? Share this post Link to post Share on other sites
Posted 18 Feb 2013 I didn't made the connections with the slave yet. Because I was in hurry today I observed that I have to use CPRTCL instruction to activate the channel 2 . Now I have an error but tomorrow I will see what it is happening. Thanks. Share this post Link to post Share on other sites