Communication Protocol; Polling - RKC INSTRUMENT CB100 Instruction Manual

4. COMMUNICATION PROTOCOL

The CB100/CB400/CB500/CB700/CB900 digital controller (hereinafter, the "controller") uses the
polling/selecting method to establish a data link. The basic procedure is followed ANSI X3.28
subcategory 2.5, A4 basic mode data transmission control procedure (Fast selecting is established for
selecting).
! In the polling/selecting method, the controller is controlled completely by the host computer is
permitted. Since the host computer invites information message sending from and receiving to the
controller, send the data in accordance with the polling or selecting procedure. (Centralized control
method)
! The code use in communication is 7-bit ASCII code including transmission control character. The
transmission control characters are [EOT] (04H), [ENQ] (05H), [ACK] (06H), [NAK] (15H),
[STX] (02H) and [ETX] (03H). The figure in the parenthesis is indicating hexadecimal number.

4.1 Polling

Polling is an action that host computer requesting one of the controller which selected among
multidrop connected, to transmit the data. The procedure is as the following.
Host computer send
E
[Address] [ ID ]
O
T
(1)
(2)
ID: Identifier
IMCB03-E3
Controller send
E
No response
N
Q
E
O
T
(4)
S
[ ID ] [ Data ]
T
X
(3)
Host
computer
send
(5)
E
[ BCC ]
T
X
No
response
Indefinite
A
C
K
(7)
Host
computer
Controller
send
send
(8)
E
Time
O
out
T
(9)
(6)
N
A
K
E
O
T
(10)
19