Technical data

6-2 Bosch Rexroth AG | Electric Drives and Controls Rexroth VCP-Operating Concept | R911305038 / 01
3964 RK512
6.1 3964 RK512
The 3964/RK512 protocol allows you
– direct read-access to all PLC data
– indirect write-access to all PLC data if the supplied function block is
used
– direct write-access to all data in a data block
– bit-access to all byte-oriented data types
– byte access to all data words in a data block.
6.1.1 Procedure of the 3964 Protocol
6.1.1.1 Telegram for Connection Setup
The connection setup is initiated by the active partner. If the connection
cannot be established successfully (passive partner sends NAK), the
active partner will repeat the attempt 3 times.
If the connection setup is successful, but the passive partner transmits
a NAK after receiving the data block, the active partner will make up to
6 attempts to establish the connection and to transmit the data.
The block check must be activated if the BCC (block check character)
is to be added to the transmission.
Active Partner
(Operating Device)
Data Passive Partner
Sending STX Receiving
Receiving DLE (NAK) Sending
Sending Data Receiving
Sending DLE Receiving
Sending ETX Receiving
Sending BCC (optional) Receiving
Receiving DLE (NAK) Sending
Fig. 6-1: Connection set-up telegram for the 3964 procedure