PD 667 Profibus - Master Configuration:

Record name: DP_Master.

Softwire number: 401.

Variable name	Variable description
NumberOfSlaves	Number of active indexes in the DP_slaves array
Baud_Rate	Bus speed
MasterAddress	The master's own address
SendFDLinterval	Time between FDL and token frames
SendGlobalInterval	Time between Global control frames

NumberOfSlaves

NumberOfSlaves:

Byte;

(* factory setting 0 *)

The number of slaves to which the master must establish a communication link. The slaves are defined in DP_Slaves.

Example:

The number of slaves to which the master must establish a communication link. The slaves are defined in DP_Slaves.

NumberOfSlaves = 3 Communication will be establish with the 3 slaves defined in: DP_Slaves[1], DP_Slaves[2] and DP_Slaves[3].

Baud_Rate

Baud_Rate:

LongInteger;

(* factory setting 19200 *)

Baud rate for the Profibus network.

Allowed values:	Baud rate deviation:
9600	0 %
19200	0 %
45450	+1.4%
93750	+2.4%
187500	+2.4%

Baud rates above 19200 have a deviation greater than that specified by Profibus, and are not guaranteed to work with all slave types.

MasterAddress

MasterAddress:

Byte;

(* factory setting 0 *)

Profibus node address to be used by the master.

Permitted range: 0 .. 125

Any address can be used for the master, without any change in performance.

Address gaps are allowed.

SendFDLInterval

SendFDLinterval:

Real;

(* factory setting 0.7 *)

Timer value to control the interval of sending network management frames on the Profibus.

Time value is in seconds.

FDL requests are used by normative conform masters to search for other masters which are added to or removed from the network.

The PD 667 does not support multi master networks, but it is possible to let the master send an "FDL-request" and a "pass token" to itself, with the specified interval.

Some slave ASICs need FDL frames to control the automatic baud rate detection. To enable this function, the FDL frames must be send with a reasonable interval.

Token passing from the master to itself is done to avoid an accidentally connected additional master interfering with communication.

SendGlobalInterval

SendGlobalInterval:

Real;

(* factory setting 1.1 *)

Timer value to control the interval of sending the "global control" on the Profibus.

Time value is in seconds.

The PD 667 does not support sync and freeze functions, which are controlled by the global control message. However, some slaves have a special safety feature, implemented which monitors the master status. A master is supposed to send a global control message within a certain interval to make these slaves restart their safety timer. If the timer runs out, the slaves will assume that the master is not working and will (normally) switch off their outputs.

The Profibus master will send a "Global control" containing unsync and unfreeze commands with the interval setup by SendGlobalInterval.