Siemens 3964(R) FAQ

This document responds to the frequently asked questions concerning the Siemens 3964(R) Driver of Engiby. It also lists the basic points to check before to realize a 3964(R) connection. Please consult the appropriate document for information about versions and the last improvements.

Fupla IL program or NG-Configurator

The driver can be used with Fupla, in IL programs or with the Engiby's Configurator. Fupla with SEND/RCV Fboxes are normally used with the RK512 interpreter. The Engiby configurator allows you to configure the telegrams in a MS-Excel table. You will fined more information about the Engiby Configurator at: Engiby Configurator. IL programs are rather used when the RK512 interpreter is not needed and you must build the data package yourself.

Application example

Here you can download a simple application example. It contains a Master and a Slave CPU. The master writes and reads back some registers in the slave. If you have a correct hardware and software configuration as well as a good cabling, the communication must work without problem between 2 PCDs.

3964 or 3964(R)

The 3964 protocol is working without checksum. The 3964R is the same protocol but using a checksum. Both version are support by the driver. The option must be set according to the partner device. It is recommended to use the 3964R version if it is supported by both devices.

RK512 or No RK512 interpreter.

The RK512 interpreter is an application layer of the protocol able to access directly PLC media like flags and data blocks.

The driver can be used without interpreter with IL program. In this case it is possible to interpret each data package individually. It must be used if the partner device send data package that are not RK512 conform. The data decoding must be realized in IL code by the user. An example is also in the downloadable demo project.

The driver is also able to directly interpret the RK512 application layer and allow to directly access the PCD and the partner media. This option must be set when the link layer is configured and the RK 512 layer must be activated.

Master / Slave.

The Driver supports both, Master and Slave functions even simultaneously. However it is important to know if the PCD will be master or slave. If not absolutely required, it is not recommended to activate Master and Slave function is the same device.

Priority

Because the 3964(R) protocol is a full duplex protocol, one partner must be set to high priority while the other has low priority. This property must be set in the link layer.

Supported functions as Master

Check that the required functions are supported. Contact Engiby if further functions are desired.

Supported functions as Slave and interpretation.

Check that the required functions are supported. Contact Engiby if further functions are desired.

Hardware connection

The 3964(R) is a point to point protocol only. Therefore, the driver supports RS232 and point to point RS422 connection only. Hardware handshake is not needed for the driver. The CTS and the DTR outputs are set to High and can be used if required by the partner device.

Using the port 0 / PGU

The PGU is the port 0 on all actual PCD systems. It can be used with the following restrictions: The option 'Full RS-232 Handshaking' must be checked in the Device Configurator under RS232/PGU.
If the port 0 needs to be used as PGU line (not in full handshake), no PGU cable must be plugged in when the PCD starts. If a PGU cable is connected, the driver is disabled and the line is forced in PGU mode. The PCD must be restarted after disconnecting the PGU cable.

Value format

Basically the 3964(R) protocol can supports various value formats and this is a matter of both partner devices. The PCD has 32 bits registers. The Fupla Fboxes have an option to convert all common data formats (8 bits, 16 bits and 32 bits). In case of doubt, only a test can determine if values are compatible or must be converted. Contact Engiby if further format conversions are needed.
Floating point values (32 bits) can also be exchanged.

Addressing

The address is made of the bytes 5 and 6 of the header. For a PCD Master, the address of the available values in the Slaves must be known. In the SEND and RCV Fbox, addresses are given in integer format. Convert Hex format to integer if necessary.
For a PCD Slave, all resources (except big data blocks) are available by the Master. Be sure the Master doesn't access the dynamic allocated resources.
Addressing registers: If the address is given as DB address and offset in the master, the corresponding register in the PCD is:
            (DB address * 256) + offset
The fact that the offset is interpreted as byte, word or long word in the master does not affect the calculation of the register address in the PCD as slave.

Performances

The performance of the driver depends on the transmission speed and the reaction time of the CPU.
The reaction time of the CPU is affected by:

• The number of values asked or sent in each requests: Less values = faster response.
• Other applications: each application extends the cycle and the reaction time.
• The other serial connections: Each active serial line will reduce the performance.
• The protocol version: The performance is slightly reduced with 3964R.

Memory used

The driver including the RK interpreter function uses the following capacity:

For the Master function, the reported values is the minimum without any Send/Receive command. A supplementary memory will be used for each Send/Receive command.
The needed memory may vary depending on the PG4/PG5 version used and selected options.
These values have been noted with the version 2.0.140 of the Siemens driver and with PG5 version 1.1.050. Usually, each new version needs more memory.

Load on the CPU

The maximum load on the CPU is reached during data request (Receive function) for a Slave and during Data transmission (Send function) for a Master. It depends on the amount of transferred values. The following measurement has been made with the Driver version 2.0.140.

Conditions:

• System PCD2.M120 with Firmware 082
• Protocol 3964(R) with RK 512, 9600 Bauds.
• Serial line 1, PGU active on line 0.
• CPU Load set to 20%
• No other program in the PCD.
• The Master is a PCD with the same Siemens 3964(R) driver.
• Telegrams: Master Read/Writes 32 bits integer values from the Slave.

Maximum cycle time measured on the Slave:

The CPU load of the driver may also be adjusted through an option in the Link layer. The CPU power used by the driver can be increase but will slow down the other applications. Note that communication tasks supported by the firmware have higher priority: 
- PGU port
- S-Bus protocol
- Profibus DP and FMS
- LON module
- IP module

Public Line Modem

Connection over public line modem is not yet supported by Master and Slave.

Leased Line Modem

Leased line modem is not yet implemented.

Gateway

Gateway function can be realized on request.

Siemens 3964(R) over TCP/IP

Not yet implemented. Contact Engiby for possible solutions.

Prices of licenses for Siemens 3964(R) Driver