4. FUNCTIONS
MELSEC-A
4-2
4.3 Communication
Relationship
In PROFIBUS, all of the connection information must be written in CRL (Communication Relationship
List) as communication relationships (hereafter abbreviated as communication). Communication
contains connection oriented communication that is required for establishing logical circuits before
communication and connection less list communication that does not have data communication
certainty when establishing logical circuits before communication is not required. In addition, it also
contains FMS communication and FMA7 communications.
The following communication types are prescribed for FMS communication.
MMAC
(Master to Master Acyclic Connection)
MSAC
(Master to Slave Acyclic Connection)
MSAC_SI
(Master to Slave Acyclic Connection/Slave Initiative)
MSCY
(Master to Slave Cyclic Connection)
MSCY_SI
(Master to Slave Cyclic Connection/Slave Initiative)
BRCT (Broadcast)
MULT (Multicast)
In addition, the communications other than BRCT and MULT have the following attributes:
/D : Defined connection
/I : Request open connection
/O : Responder open connection
However, MSxx's /O connections are not allowed. (PROFIBUS standard) Of these, BRCT and
MULT are connectionless communications and the others are connection oriented communications.
All FMA7 communications are connection oriented.
In AJ71PB96F/A1SJ71PB96F, the above all communications are enable to use by using the software
package.
In AJ71PB96F/A1SJ71PB96F, when the following conditions are met the maximum number of
communications including FMA7 communications can be set to 32. In other cases the maximum
number of communications that can be set is 16.
(1) Communication
type
conditions
Communications are divided into the following two types.
Category I
MMAC
(Master to Master Acyclic Connection)
MSAC
(Master to Slave Acyclic Connection)
MSCA_SI
(Master to Slave Acyclic Connection/Slave Initiative)
SMA7 communication
Category II
MSCY (Master
to
Slave
Cyclic
Communication)
MSCY_SI (Master
to
Slave
Cyclic
Communication/Slave
Initiative)
BRCT (Broadcast)
MULT (Multicast)
The number of communications must satisfy the following formula.
Category I number of communications
×
2 + Category II number of communications
≤
32
(2) PDU
size
conditions
All of the PDU sizes for all communications shall be 200 or less.