Supported device types and versions
Communication line configuration
Communication station configuration
I/O tag configuration
Literature
Changes and modifications
Document revisions
The protocol allows reading and writing data from control PLC automats of Siemens Simatic of the S5 and S7 series. PLC Simatic must be equipped with the following serial communication point-to-point modules:
The protocol RK512 is a transport superstructure of protocol 3964(R). It allows universal reading and writing values of PLC Simatic objects - minimal intervention into the PLC application software (using the STEPS5/7 programming language).
The 3964 protocol, which is the line layer of the RK512 protocol, has two variants - 3964 a 3964R. The 3964R allows extra data security using the BCC checksum.
The Communication station configuration dialog box - tab Protocol parameters.
Parameters defined in the input field have an effect on some optional protocol parameters. The following station protocol parameters can be defined:
Table 1
| Parameter | Meaning | Unit / size | Default value |
|---|---|---|---|
| Maximum count of request retries. If no response returns after a request had been sent, the station's status will change to a communication error. | - | 2 | |
| Timeout before resending a request if no response has been received. | ms | 100 ms | |
| The delay after sending the request and before reading the response. | ms | 100 ms | |
| The delay between the response readings. | ms | 50 ms | |
| The maximum number of retries of the response reading. | - | 40 | |
| Enable the 3964 link protocol, i.e. version with no transmission security. By default, the 3964R protocol is used, which implements the BCC checksum. | YES/NO | NO | |
| CPU identification (1 up to 4), not used by default (value = 0). | 0,1,2,3,4 | 0 |
Possible I/O tag value types: Ai, Ao, Ci, Co, Di, Do.
I/O tag address is a character string as follows:
Table 2
| Data | Format | Description | Access | I/O tag type |
|---|---|---|---|---|
| Data block/Extended data block elements | D{B|X}mD{L|R|W|D}n[x] | m = "data block" number n = word offset in the data block x = suffix KF,KG (as necessary - see Note 1) | R/W | Ai, Ao, Ci, Co |
| Data block bits | D{B|X}mDn.k | m = "data block" number n = word offset in the data block k = bit position [0..15] | R/W | Di, Do |
| Memory elements | F{Y|W|D}n[x] or M{B|W|D}n[x] | n = byte offset in "memory area" x = suffix KF, KG (as necessary - see Note 1) | R | Ai, Ci |
| Memory bits | Fn.k or Mn.k | n = byte offset in "memory area" k = bit position [0..7] | R | Di |
| Input elements | I{B|W|D}n[x] or E{B|W|D}n[x] | n = byte offset in "input area" x = suffix KF, KG (as necessary - see Note 1) | R | Ai, Ci |
| Input bits | In.k or En.k | n = byte offset in "input area" k = bit position [0..7] | R | Di |
| Output elements | Q{B|W|D}n[x] or A{B|W|D}n[x] | n = byte offset in "output area" x = suffix KF, KG (as necessary - see Note 1) | R | Ai, Ci |
| Output bits | Qn.k or An.k | n = byte offset v "output area" k = bit position [0..7] | R | Di |
Table 2 contains the address format used in SIMATIC S5, i.e. use of word offset in DB and DX elements. Therefore you can use addresses in the S7 format according to table 3 for DB and DX elements:
Table 3
| Data | Format | Description | Access | I/O tag type |
|---|---|---|---|---|
| Data block/Extended data block elements | D{B|X}m.DB{B|W|D}n[x] | m = "data block" number n = byte offset in the data block x = suffix KF, KG (as necessary - see Note 1) | R/W | Ai, Ao, Ci, Co |
| Data block bits | D{B|X}m.DBXn.k | m = "data block" number n = byte offset in the data block k = bit position [0..7] | R/W | Di, Do |
Explanatory text:
Note 1:
The suffix is optional as follows:
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