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IMR02F04-E1
3. RKC COMMUNICATION PROTOCOL
The PG500 uses the polling/selecting method to establish a data link.
The basic procedure is followed ANSI X3.28-1976 subcategories 2.5 and A4 basic mode data transmission
control procedure (Fast selecting is the selecting method used in this PG500).
The polling/selecting procedures are a centralized control method where the host computer controls
the entire process. The host computer initiates all communication so the PG500 responds according to
queries and commands from the host.
The code use in communication is 7-bit ASCII code including transmission control characters. The
transmission control characters are EOT (04H), ENQ (05H), ACK (06H), NAK (15H), STX (02H)
and ETX (03H). The figures in the parenthesis indicate the corresponding hexadecimal number.
3.1 Polling
Polling is the action where the host computer requests one of the connected PG500s to transmit data.
An example of the polling procedure is shown below:
Host
computer
send
Host
computer
send
Host computer send
PG500
send
PG500 send
E
O
T
E
O
T
E
N
Q
E
O
T
E
T
X
S
T
X
E
O
T
A
C
K
N
A
K
[ Data ]
[ BCC ]
[ ID ]
(1)
(2)
(5)
(3)
(4)
(9)
(7)
(10)
[Address] [ ID ]
No response
No
response
Indefinite
Time
out
ID: Identifier
(8)
(6)
