Applies To:
  • CitectSCADA 5.xx

Citect supports communications to the Siemens S7 PLC using what is called the "SSEVEN" driver. One of the driver components of the Beta SSEVEN driver was the SSEVEN.DLL. I heard that the SSEVEN driver has been integrated into Citect V5.21. I am now using a fresh installation of Citect V5.21 and cannot find this driver in Citect's BIN directory, although it is meant to be included with the product. Why? 

The SSEVEN driver is now 4 separate DLLs: S7WIN, S7NT, S7WINSP, S7NTSP. Previously in the Beta releases, there were two DLLs (one for Windows 95/98 and one for Windows NT) which were both named SSEVEN.DLL. Use of the beta driver relied on the user copying the correct one into the Citect\Bin directory. There was no definitive way of distinguishing between each version of the DLL, and only one could be present at any one time. Now, with separate DLLs, it is easy to distinguish between them.

The DLLs purposes are as follows:

S7WIN:  Windows 95/98 version of the SSEVEN driver
S7NT:  Windows NT version of the SSEVEN driver
S7WINSP:  Windows 95/98 'Special Purpose' version of the SSEVEN driver
S7NTSP:  Windows NT 'Special Purpose' version of the "SSEVEN" driver

Note: the reason for the 'Special purpose' version is described in the online help distributed in Citect V5.20 Driver Pack and Citect V5.21.

The SSEVEN.DLL has been superceded.