S7-300 communication with SLC-504

[Mushu]

Hi, I have post this in the Allen Bradley post, it is very urgent. We have a plant with an Allen Bradley PLC; this is communicating with an Intouch trhough RS-232. A new machine is going to be implemented in the plant; it has a Siemens S7-300 PLC. The programme is ready to communicate through Ethernet (functions "AG_SEND" and "AG_RECV" are used). I asked to some colleges and they think the existing PLC will not communicate properlly with Ethernet. Do you have any idea how could it be done? I am completly lost in this. thanks

[JesperMP]

There is no easy way. But I know of two possible ways to communicate between S7 and AB: 1. Install a CP341 with "loadable drivers" in the S7-300 rack. Siemens has a driver for the DF1 protocol that most (but not all) AB PLCs also use. You can then communicate natively between the two PLCs via DF1. 2. Connect both PLCs to a PC, and then let the PC act as a middleman in the communication via OPC. You will need an RSLinx OEM license, a Simatic Softnet Ethernet license, and an OPC client that does the datatransfer between the two OPC servers. edit: I just notice that you are allready using the serial port on the AB PLC to communicate with Intouch. If Intouch uses OPC, then you may allready have half of solution 1. If Intouch do not use OPC, then you have an additional problem. You need another free comms path as the serial port is spent on the Intouch connection. This maybe leads to solution 3: 3. Let Intouch be the middleware. I only recommend this if the connection between the S7 and AB PLCs are "not so critical". You can connect Intouch to the S7 PLC via its own driver. Then do the dataexchange in Intouch via a script. And what EXACTLY are the type of PLCs you are using ? edit again: I see in the AB section that the AB is an SLC5/04. This leads to solution 4: 4. If the datexchange is critical, and the timing is also critical then a radical and efficient way is to install a Profibus slave card in the SLC rack. SST (aka Woodhead) makes such cards for the SLC platform. The S7 must then have either onboard Profibus (S7-314C-2DP, or S7-315, or S7-317 or S7-318), or there must be a Profibus card in the S7 rack (CP342-5). Edited September 22, 2005 by JesperMP