What do I need for my automation device ?You have a certain PLC and want to know how to connect.Device fundamentals for Simatic-Newbies, may also be used as a compendium for professionals. In the following table we give an overview on devices that can be accessed using our software products. This list is certainly incomplete. The list mainly contains old S7 CPs for ethernet, because the new CPs all support the needed functionality. There are also some other suppliers of Simatic CPs, some of them we have tested. PLEASE NOTE:
Communication using TCP/IPrktcp_server basicsrktcp_server supports the both protocol types S5 compatible communication in FETCH-WRITE mode andS7 communication in put and get mode over TCP for data exchange with Simatic plcs. The S5 compatible communication is supported in TCP-native as well as ISO-on-TCP (RFC1006). This means that you can connect to all devices (CPs) that offer one of these modes, giving you a reliable data connection. If you use the S5 compatible communication and you have the choice between TCP-native and ISO-on-TCP, most often TCP-native will be the best choice. -------- Why TCP-native?The S5 comptible communikation provides by definition a block orientated telegram mode, therefore, there in no need to use a block orinetated layer below.On all tested CP 443-1, the TCP-native is a little bit faster than ISO-on-TCP. -------- Why nevertheless ISO-on-TCP?There are a lot of existing implementations with older CPs, mainly the 6GK7 443-1EX02, for which the partner pc needs to be substituted. To support also these implementations, we have implemented ISO-on-TCP (RFC1006).-------- Remarks to S7 communicationThe S5 compatible communication protocol is published by Siemens. The S7 communication is not published, it is "factory private". All other suppliers of S7 communication have "re-engineered" this protocol.But: If Siemens would change this protocol, building new CPs, which do not support the actual protocol version, they would also produce a incompatibility between the older and actual CPs and new ones, meens: in the own family. We do not assume, that this will happen: The protocol header of the S5 compatible commmunication was defined in the 2nd half of the eighties, the RK512 protocol is much older,it was defined 10 years earlier. Both are still supported. This long time support of old standards is one of the reasons for the success of the Simatic family: The clients can be shure that their once made investments will not be lost, over rolled by new non-backward compatible technologies. ( We do not talk about operation panels, here :-( ) We agree: Re-engineering always is a risc, but we have only implemented a small subset of the complete definition of the PDU. This enables a very extensive analysis of the reactions and very intensive tests. ----------- Why not SEND-RECEIVE ?SEND-RECEIVE implements a unidirectional point to point connection over a net.Runtime software inside the CPU is needed.FETCH-WRITE implements a client-server-connection over a net. The CP is processing the whole communication. From the technical point of view, it would be a back step, to use SEND-RECEIVE. In addition: On initiating SEND-RECEIVE by the built-in-functions, we missed some functionalities, which a needed to guarantee a secure data transport. ( When we have started with the implementation of the rktcp_server, we have also made some tests with SEND-RECEIVE and we have seen some really funny effects.) S7-400the rapid solution over TCP
A quick-check-method: Testing results are very welcome, also about CPs that come from other manufacturers than Siemens. S7-300the rapid solution over TCPHint: On Simatic S7-300 systems the internal data transfer between CPU and CP works serial with 187.5 kBit/s. Therefore you should not expect too much speed from the Ethernet-link: The maximum data rate will be about 5 kByte/s.
Especially on Ethernet CPs there have been a lot of changes. Therefore it is strongly recommended to test the combination before ordering the server. A quick-check-method: Testing results are very welcome, also from CPs which are not from Siemens. S5 all plc 115U / 135U/ 155U -Seriesthe rapid solution over TCPSiemens: CP1430 TCPThe CP1430 TCP was not testet by us, but according to the informations in the Siemens cataloque and Simatic hotline it should work.Some of our customers use it together with rktcp_server. INAT : S5-TCP/IPThe company INAT offers a communications processor called S5-TCP/IP for the Simatic S5 families 115U, 135U and 155U. We have tested this CP and it works fine. This CP supports TCP/IP with and without RFC1006, H1, FTP and all of these at the same time. According to INAT, it is often used to increase existing installations to more communications capabilities.While testing this CP, we were surprised about the high transfer performance of this product.
S7 & S5 : Communication using RK512With rk512_server you can connect to SIMATIC S5 and SIMATIC S7.Below you find a List of devices that make it possible. Normally a communication unit (CP) is used; the CP must be configured by the user. Siemens provides especial programming software for this purpose. CPs are available with different interfaces. RS-232C has the advantage that it can most simply be connected to PCs, but has a limited line length of about 15 meters. Also galvanic isolation is most often missing. The other interface types (RS422 and 20mA) provide distances of about 1000m. This is about 6 times the length of a 10Mbit-Ethernet-Segment (10Base-T), however you need a conversion box next to the PC or (sometimes better) a special interface board inside the PC. Some CPs need RUNTIME-Software in the PLC to operate properly or at all. S7- Family( Refer also to Siemens catalog ST70 )S7 - 300The tiny solution: The CP340 can talk 3964R only, but Siemens provides RK512 emulation software, which you can get via Internet, pay with Simaticard. This emulation however does not provide full data speed: only about 800 Byte/s can be reached. CP340
Standard solution: CP 341 with builtin RK512. Max. speed usable with common PC hardware is 38400 bps. You may also use CP 341 -1 which provides 57600 bps additionally. CP341
S7- 400CP441-2
CP 441-2 can operate with 2 interfaces simultanously.
S7-400 und 300 via MPI-ConverterIn certain environments you may use an MPI-Adaptor; this is a small and cheap box which converts serial RK512 to the MPI-protocol. This gives you access to all S7-CPUs connected to the MPI-bus.
S5 - Family( Refer also to Siemens catalogue ST50 )S5-95U
The device S5-95U with second serial interface can speak 3964R; the interface is available as TTY/20mA current loop only.
115U - tiny solutions:
CPU944B
with second serial interface and operating system unit 3964R can communicate over 20mA current loop at 9600 bps.
CPU945
with second serial interface: CPU 945 B
135U - tiny solution:CPU 928B with second serial interface already speaks RK512, you have to chose an interface type: CPU 928 B
All devices of 115U / 135U / 155U:You may attach communication units CP524 and CP544. CP 524 has a single interface, you must chose an interface module: CP 524
The CP 544 can operate with two interfaces; the sum of their speeds must not be faster than 76800 bps. CP 544
Fossils( their robustnes is the reason that you can still find them )
Communication using AS511Our rk511_server gives to you access to all SIMATIC S5-CPUs except. Connection is realized via the Programming device interface. If you want to use standard PC serial ports, you probably need a converter box. A better way may be the usage of a Current loop adapter board.
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