Micromod Micro-DCI: 53SL5100A Single Loop Controller - Manual (Page 136)

Single Loop Process Controller Instruction Manual
128 Communications
B.1.3 Message Types
The types of messages that are sent between the host or SUPERVISOR-PC and the Datalink network
instrument are formatted as follows:
B.1.3.1 Host or SUPERVISOR-PC to Instrument:
1. INTERROGATE - This message requests up to 20H consecutively stored bytes, beginning at
the specified memory address location of the addressed instrument.
01111110 EOH + I.A. NUM LO ADD HI ADD LRC
2. CHANGE - This message sends up to 20H bytes of new data to the addressed instrument.
01111110 AOH + 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
addressed instrument. (NUM = 2n)
01111110 COH + I.A. NUM LO ADD HI ADD Mask 1 State 1 XXXX Mask N
State N LRC
4. ACKNOWLEDGE - This message signals the addressed instrument that its last echoed
change message was received correctly; the instrument performs the change requested.
01111110 80H + I.A.
B.1.3.2 Instrument 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 20H + I.A. NUM LO ADD HI ADD Data 1 XXXXX Data N LRC
B.1.4 Communication Transaction Examples
B.1.4.1 Transaction A Example
Host or SUPERVISOR-PC requests 9 bytes of data beginning at hexadecimal memory address 1000H
from the instrument at Datalink address 03.
1. Host or SUPERVISOR-PC sends INTERROGATE message.
01111110 11100011 00001001 00000000 00010000 11111100
SOH Command NUM LO ADD HI ADD LRC
+ I.A.
2. Instrument sends RESPONSE message.
01111110 00100011 00001001 00000000 00010000 XXXXX XXXXX XXXXX LRC
SOH Command NUM LO ADD HI ADD Data 1 .................Data 9
+ I.A.