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CP-441-2 with Honeywell DCS through DCS terminal server using Rs485 and the Protocol is Modbus

Created by: tonybala at: 10/25/2008 3:26 PM (1 Replies)

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10/25/2008 3:26 PM	Rate (1)
tonybala Posts: 1 Rating: (1)	Hi, I am new to the Siemens PLCs. I have connected CP-441-2 with Honeywell DCS through DCS terminal server using Rs485 and the Protocol is Modbus. My communication settings at CP-441-2 end is 19200,8bits,parity none,stop bit 1. It is same in the DCS side also. But my CP-441-2 RXD1 blinks once in 2 minutes. TXD1 never blinks. Could any one please help me to find out what could be the Problem. I also use 1 MB flash memory card I want to download the entire program in to PLC then I want to force each points in the PLC to DCS register Map to see if it is correctly configured in the other end. Please help me on this
tonybala Posts: 1 Rating: (1)	Last edited by: CS Moderator at: 10/27/2008 12:53 PM new subject after splitting
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10/26/2008 1:11 PM	Rate (1)
dchartier Grandmaster-Expert Joined: 9/27/2006 Last visit: 3/23/2025 Posts: 12344 Rating: (2707)	tonybala I have connected CP-441-2 with Honeywell DCS through DCS terminal server using Rs485 and the Protocol is Modbus. My communication settings at CP-441-2 end is 19200,8bits,parity none,stop bit 1. It is same in the DCS side also. But my CP-441-2 RXD1 blinks once in 2 minutes. TXD1 never blinks. Could any one please help me to find out what could be the Problem. Hello Tony; A few assumptions first (yes, i know we should never assume...): The protocol is Modbus RTU. The Honeywell DCS is master, the CP 441-2 is setup as slave Access to the Modbus slave manual here Good point, if your Rx LED is blinking, it shows that the electrical connection between the 2 units is good; doesn't mean that it is validated for the protocolthough, but it is better than no LED at all. Now for some questions: How did you parametrize the CP 441-2, how is it setup. Did you create a PtPconnection in Netpro? The connection ID number is required in the communication FB180 Parameter "ID") The properties of the CP 441-2 have been correctly setup for Modbus (baudrate, parity...) you sayThe parameters have been correctly downloaded to the CPU? (Just checking...) Please show a screencapture of your FB180 call in OB1, we probably need to see how it has been setup to help you out. Have you inserted a rising edge on the input parameter "CP_Start" in OB100, to initialize the CP in the CPU startup? Which Modbus function codes (and lengths) are requested by the master, and how did you associate the native S7 addresses to the Modbus (Modicon) addressing for the different Modbus functions? The manual suggested above has some information on these (and many other) aspects of setting up a CP 441-2 as Modbus slave. And there are chapters on the diagnostics of the CP 441-2, starting with LEDS decoding, use of the diagnostic buffer of the CP (through the Onlive view of the Hardware Config editor) and the Systat message area of the instance DB of FB180. But we also will be here to give a hand, so come back to the forum withany otherquestions or clarifcations. I also use 1 MB flash memory card I want to download the entire program in to PLC then I want to force each points in the PLC to DCS register Map to see if it is correctly configured in the other end. A 1 MB flash EEPROM card will hold all your program. The easiest way to monitor and modify the data in the PLC is through a VAT table. This is a block (you create them iin the program's Blocks folder) where you can insert the register addresses you want to look at (single, or a group of them, practical if the addresses are contiguous); you then use the "glasses" icon to go Online and collect the data values associated with the addresses. You can also write values to these registers; this is not exactly a Force, because values in a VAT will be overwritten by the program cycle if there is logic connected to them. But from the VAT table you can go to a Force table (see the online help of Step 7) where you can force the values you want. there are restrictions o the type of addresses you can force. And when you enter Force mode, a yellow LED appears on the CPU, because it is not a "normal" mode of operation for the CPU: the output image is not transfered normally to the outopus, so there is no guarantee of correctoperationin this mode. Hope this helps, Daniel Chartier

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