ABB ControlIT 53MC5000 - Page 343

B.1.3 MESSAGE TYPES
The types of messages that are sent between the host or SUPERVISOR-PC and the Datalink net-
work controller are formatted as follows:
HOST OR SUPERVISOR-PC TO CONTROLLER:
1.
INTERROGATE
- This message requests up to 20
H
consecutively stored bytes, beginning at
the specified memory address location of the addressed controller.
01111110 E0
H
+ I.A. NUM LO ADD HI ADD LRC
2.
CHANGE
- This message sends up to 20
H
bytes of new data to the addressed controller.
01111110 A0
H
+ I.A. NUM LO ADD HI ADD Data 1 XXXXXXXXX Data N LRC
3.
CHANGE BITS
- This message alters only the specified bits in the specified bytes in the ad-
dressed controller. (NUM = 2n)
01111110 C0
H
+ I.A. NUM LO ADD HI ADD Mask 1 State 1 XXXX Mask N
State N LRC
4.
ACKNOWLEDGE
- This message signals the addressed controller that its last echoed change
message was received correctly; the controller performs the change requested.
01111110 80
H
+ I.A.
CONTROLLER TO HOST OR SUPERVISOR-PC:
1.
RESPONSE
- This message furnishes the data requested by the INTERROGATE command of
the Host or SUPERVISOR-PC. It is also used to echo back the previous CHANGE message of
the Host or SUPERVISOR-PC.
01111110 20
H
+ I.A. NUM LO ADD HI ADD Data 1 XXXXX Data N LRC
53MC5000 Process Control Station
B-4