RKC INSTRUMENT FAREX SR MINI SYSTEM - 4. COMMUNICATION PROTOCOL; 4.1 Polling

IMSRM04-E8
25
4. COMMUNICATION PROTOCOL
To establish the data link, the polling/selecting method is employed. The basic procedure follows
ANSI X 3.28 subcategory 2.5, B1 and JIS basic data transmission control. For selecting, fast selecting
is employed.
z
In the polling/selecting method, the device is entirely controlled by the host computer to allow
only data transfer with the host computer. In order to make the device send or receive data
messages, send the messages from the host computer in accordance with the polling or selecting
procedure (Centralized operation).
z
For communication, ASCII codes including transmission control characters are used.
Transmission control characters used in the device:
EOT (04H), ENQ (05H), ACK (06H), NAK (15H), STX (02H), ETB (17H), ETX (03H)
( ) : Hexadecimal number
4.1 Polling
Polling is an action that host computer requesting one of the device which selected among multi-drop
connected, to send the data. The polling procedure is as follows.
Polling procedure
SR Mini
SYSTEM
send
SR Mini SYSTEM send
ID: Identifier
Host
computer
send
Host
computer
send
Host com
p
uter send
E
O
T
E
O
T
[
Data
]
or
[
BCC
]
[
ID
]
(1)
(2)
(5)
(3)
(4)
(9)
(7)
(10)
[
Address
]
[
ID
]
No res
p
onse
No
response
Indefinite
→→→
→
→
→
→
→
(Next data
send)
→
Time
out
→
(Same
data
send)
←
←
←
E
O
T
E
O
T
S
T
X
A
C
K
N
A
K
E
T
B
E
N
Q
(8)
(6)
E
T
X