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node-red-contrib-s7

A Node-RED node to interact with Siemens S7 PLCs.

This node was created as part of the ST-One project.

Install

You can install this node directly from the "Manage Palette" menu in the Node-RED interface.

Alternatively, run the following command in your Node-RED user directory - typically ~/.node-red on Linux or %HOMEPATH%\.nodered on Windows

    npm install node-red-contrib-s7

NodeJS version 10 or greater and Node-RED version 1.0 or greater is required.

Usage

Each connection to a PLC is represented by the S7 Endpoint configuration node. You can configure the PLC's Address, the variables available and their addresses, and the cycle time for reading the variables.

The S7 In node makes the variable's values available in a flow in three different modes:

Variable addressing

The variables and their addresses configured on the S7 Endpoint follow a slightly different scheme than used on Step 7 or TIA Portal. Here are some examples that may guide you on addressing your variables:

AddressStep7 equivalentJS Data typeDescription
DB5,X0.1DB5.DBX0.1BooleanBit 1 of byte 0 of DB 5
DB23,B1 or DB23,BYTE1DB23.DBB1NumberByte 1 (0-255) of DB 23
DB100,C2 or DB100,CHAR2DB100.DBB2StringByte 2 of DB 100 as a Char
DB42,I3 or DB42,INT3DB42.DBW3NumberSigned 16-bit number at byte 3 of DB 42
DB57,WORD4DB57.DBW4NumberUnsigned 16-bit number at byte 4 of DB 57
DB13,DI5 or DB13,DINT5DB13.DBD5NumberSigned 32-bit number at byte 5 of DB 13
DB19,DW6 or DB19,DWORD6DB19.DBD6NumberUnsigned 32-bit number at byte 6 of DB 19
DB21,R7 or DB21,REAL7DB21.DBD7NumberFloating point 32-bit number at byte 7 of DB 21
DB2,S7.10*-StringString of length 10 starting at byte 7 of DB 2
I1.0 or E1.0I1.0 or E1.0BooleanBit 0 of byte 1 of input area
Q2.1 or A2.1Q2.1 or A2.1BooleanBit 1 of byte 2 of output area
M3.2M3.2BooleanBit 2 of byte 3 of memory area
IB4 or EB4IB4 or EB4NumberByte 4 (0 -255) of input area
QB5 or AB5QB5 or AB5NumberByte 5 (0 -255) of output area
MB6MB6NumberByte 6 (0 -255) of memory area
IC7 or EC7IB7 or EB7StringByte 7 of input area as a Char
QC8 or AC8QB8 or AB8StringByte 8 of output area as a Char
MC9MB9StringByte 9 of memory area as a Char
II10 or EI10IW10 or EW10NumberSigned 16-bit number at byte 10 of input area
QI12 or AI12QW12 or AW12NumberSigned 16-bit number at byte 12 of output area
MI14MW14NumberSigned 16-bit number at byte 14 of memory area
IW16 or EW16IW16 or EW16NumberUnsigned 16-bit number at byte 16 of input area
QW18 or AW18QW18 or AW18NumberUnsigned 16-bit number at byte 18 of output area
MW20MW20NumberUnsigned 16-bit number at byte 20 of memory area
IDI22 or EDI22ID22 or ED22NumberSigned 32-bit number at byte 22 of input area
QDI24 or ADI24QD24 or AD24NumberSigned 32-bit number at byte 24 of output area
MDI26MD26NumberSigned 32-bit number at byte 26 of memory area
ID28 or ED28ID28 or ED28NumberUnsigned 32-bit number at byte 28 of input area
QD30 or AD30QD30 or AD30NumberUnsigned 32-bit number at byte 30 of output area
MD32MD32NumberUnsigned 32-bit number at byte 32 of memory area
IR34 or ER34IR34 or ER34NumberFloating point 32-bit number at byte 34 of input area
QR36 or AR36QR36 or AR36NumberFloating point 32-bit number at byte 36 of output area
MR38MR38NumberFloating point 32-bit number at byte 38 of memory area
DB1,DT0-Date**A timestamp in the DATE_AND_TIME format
DB1,DTZ10-Date**A timestamp in the DATE_AND_TIME format, in UTC
DB2,DTL2-Date**A timestamp in the DTL format
DB2,DTLZ12-Date**A timestamp in the DTL format, in UTC
DB57,RWORD4DB57.DBW4NumberUnsigned 16-bit number at byte 4 of DB 57, interpreted as Little-Endian
DB13,RDI5 or DB13,RDINT5DB13.DBD5NumberSigned 32-bit number at byte 5 of DB 13, interpreted as Little-Endian
MRW20MW20NumberUnsigned 16-bit number at byte 20 of memory area, interpreted as Little-Endian

Notes on S7-1200/1500

These newer PLCs offer an "extended" version of the S7 Protocol, while we have only a "basic" version of it.

Therefore, some additional configuration steps on the PLC are necessary:

Notes on Logo! 8

On the newest Logo! 8.FS4 (and possibly 0BA8) Logic modules there is no need to set the Mode to TSAP any more, instead the default Rack/Slot value of 0/2 works just fine.

The following table shows memory areas accessible without additional settings in the controller program:

Note: These memory areas seem to be read-only from outside the controller, as they are directly used by the function blocks listed in "Logo Block" of the table

Logo BlockLogo VM Rangeexample Node-RED addressDescription
I1024 - 1031DB1,BYTE1024 or DB1,X1024.5 or DB1,WORD1024Reads input terminals 1...8 or 6 or 1...16
AI1032 - 1063DB1,WORD1032Reads analog input terminal 1. Always word sized.
Q1064 - 1071DB1,BYTE1064 or DB1,X1064.5 or DB1,WORD1064Reads output terminals 1...8 or 6 or 1...16
AQ1072 - 1103DB1,WORD1072Reads analog output terminal 1. Always word sized.
M1104 - 1117DB1,BYTE1104 or DB1,X1104.5 or DB1,WORD1104Reads bit flags M1...M8 or M6 or M1...16
AM1118 - 1245DB1,WORD1118Reads analog flag 1. Always word sized.
NI1246 - 1061DB1,BYTE1246 or DB1,X1246.5 or DB1,WORD1246Reads network input 1...8 or 6 or 1...16
NAI1262 - 1389DB1,WORD1262Reads analog network input 1. Always word sized.
NQ1390 - 1405DB1,BYTE1390 or DB1,X1390.5 or DB1,WORD1390Reads network output 1...8 or 6 or 1...16
NAQ1406 - 1469DB1,WORD1406Reads network output 1. Always word sized.

On the other hand, Logo memory areas VM 0-849 are mutable from outside the controller, but they need to be mapped into the Logo program. Without mapping, data written into these addresses will have no effect on program execution. Used VM addresses in the range mentioned above can be read/written from/into in the Logo program using the "Network" function blocks (in the function block setup use the "Local variable memory (VM)" option to map VMs to the function block).

Some addressing examples:

Logo VMExample Node-RED addressDescription
0DB1,BYTE0R/W access
1DB1,X1.3R/W access Note: use booleans
2..3DB1,WORD2R/W access
4..7DB1,DWORD4R/W access

Bugs and enhancements

Please share your ideas and experiences on the Node-RED forum, or open an issue on the page of the project on GitHub

Support

Community support is offered on a best-effort basis via GitHub Issues. For commercial support, please contact us by sending an e-mail to st-one@st-one.io.

License

Copyright: (c) 2016-2022, ST-One Ltda., Guilherme Francescon Cittolin guilherme@st-one.io

GNU General Public License v3.0+ (see LICENSE or https://www.gnu.org/licenses/gpl-3.0.txt)