ComSiemens library

PLCnext Engineer
1

Hi, I have a questions about ComSiemens library: 1) How many bytes is possibile to exchange between an AXC F 2152 and a S7-1500? 2) Is possibile to exchange LREAL data types? 3) How many S7-1500 could be read with one AXC F 2152? My customer needs to read 200 LREAL from one or (if possible) more S7-1500 and needs to log this data every 5 s. I think is too fast, what dou you think? Thanks in advance.

2

HI Alberto, Here are the answers from the developer of that FB library: ======================================================== 1. The length of Bytes which can be transmitted in one telegram is communicated between S7-CPU and PxC-CPU. And the maximum length is shown at the Output “iMaxDataCount” at the Functionblock CoSi_ETH_S7_Link. Reading all LREALS together is not possible 200 LREAL = 1600 BYTE → Minimum 4 Read Jobs neccessary. In my tests the length between 2152 and S7-1511 CPU is 452 BYTE. 2. Yes it is possible with the S7-12xx AND 15xx CPU. But there is no Functionblock available.

The customer can program an own functionblock. The customer should use the CoSi_JobInterface for one LREAL Read process.

                                               * iJobNo ---> free number
                                               * xStartJob --> Trigger all 5s and reset after Done or Error
                                               * iDataType --> Refer to "CoSi_ETH_S7_Link.iDB_Numer" description. I think "5 (DB)" in your case.
                                               * iDB_Number --> Number of the DB in the S7 Project
                                               * iOffset --> Offset where the first LREAL starts in the S7 DB.

Offset, from which to be read/written from the Siemens PLC. The
counter/timer number is to be specified in the case of the counter/timer
data type, from which is to be read/written. In the case of all other data
types, the specification is in bytes.

                                               * iDataCount --> Length in Byte which are read out from the S7-D
                                               * xReadRequest --> Constant TRUE because this job does READ Processes
                                               * xWriteRequest --> Constant FALSE because this job does NO Write processes

With rising edge of xDone the read Data must copied out of the “CoSi_ETH_S7_Link.arrDataBuffer”.
If you want to get seperate LREAL as output use BUF_TO_LREAL with connected arrDataBuffer and following parameters: REQ = Trigger from JobInterface.xDone; BUF_FORMAT = TRUE; BUF_OFFS = 0 for the first LREAL; BUF_CNT = 8 BYTE The next LREAL starts at arrDataBuffer[8] … and so on. 3. The count of Connections is limited to the maximum number of open Sockets of the PLCnext Engineer CPU.
I could not find any information about the exact count in the datasheets. But i heared about hundreds of possible Sockets.