Siemens SIMATIC 3964(R) CW communication
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protocol
Supported device types and versions
Communication line configuration
Line protocol parameters
Communication station configuration
I/O tag configuration
Literature
Changes and modifications
Document revisions
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On the link layer, this protocol implements the Siemens SIMATIC 3964R protocol and uses it to read from and write to the PLC. The protocol only supports database block (DB) addressing 0-255.
The protocol contains the following header defined by Control Web:
Byte | Name | Description |
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1 | Id | Zone identifier ('D' = data block) |
2 | DB | Number of zone (data block) |
3-4 | DW | Word address within a zone (lower byte, upper byte) |
5 | Cmd | Command ('R' - reading, 'W' - writing) |
6-7 | Count | Number of read / written words (lower byte, upper byte) |
The protocol supports reading data from control PLC automats of Siemens SIMATIC of the S5 and S7 series. PLC Simatic must be equipped with the serial communication point-to-point modules - for more details see the decription of Siemens SIMATIC 3964(R) protocol.
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The following line protocol parameters are defined:
Parameter | Meaning | Unit / size | Default value | ||||||
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| A mode of communication:
Note: Active communication is used when Control Web is replaced by D2000. | Active Passive Passive (duplex) | Active | ||||||
| Maximum size (in bytes) of data read by a single requestl. Add to this size a 7-byte Control Web header to obtain full length of response (without duplicated DLE bytes) according to the SIMATIC 3964(R) standard. | 4 až 249 B | 128 B | ||||||
| Maximum number of request retries in case of communication error. | - | 2 | ||||||
| A delay before resending a request in case of communication error. | ms | 100 ms | ||||||
| Activates a debug info about the loaded values of I/O tags. Use this parameter only when communication must be debug because it highly uses CPU and slows down the communication. | YES/NO | NO |
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- only "DB" addresses can be used, i. e. only variables in data blocks are available.
- the protocol implements a 1-byte address of the data block, i. e. it supports addressing of data blocks 0-255
- all value types except STRING are available:
Identifier <type> | Description |
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X | Bit (boolean). Specify a bit number 0 to 7 - e.g. DB9,X8.3 |
B | Byte (8 bits unsigned). |
W | Word (16 bits unsigned). |
D | Double word (32 bits unsigned). |
CHAR | Character (8 bits signed). |
INT | Integer (16 bits signed). |
DINT | Double integer (32 bits signed). |
BCD | BCD-coded 2-byte number (0-9 999) |
LBCD | BCD-kódované 4-byte number (0-99 999 999) |
REAL | Floating point number (32 bits according to IEEE754 standard). |
LREAL | Long floating point number (64 bits according to IEEE754 standard). |
DT | Date and Time, 8 bytes in BCD format. |
TIME | Time (32 bits signed) in ms. |
TOD | Time of day (32 bits unsigned) in ms. |
- address examples:
DB3,REAL0
DB3,W4
DB3,B6
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- Ver. 1.0 - January 16th, 2020 - document creation.
- Ver. 1.1 - July 10, 2020 - Support for BCD and LBCD.
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