3. SETTING FOR COMMUNICATION
IM9000F02-E2
20
RS-485 (2-wire system) send/receive timing
The transmission and reception of RS-485 communication are operated by a transmitting wire.
Therefore, the timing of switching should be acted correctly. Send/receive example in the host
computer and REX-F9000 is show in the following.
z
Polling procedure
E
O
T
E
N
Q
A
C
K
N
A
K
S
T
X
B
C
C
or
… …
… …
c
d
e
H ost
com puter
R E X-F 9000
S end
data
(P os sible/
Im poss ible)
S end
data
(P os sible/
Im poss ible)
S ending
status
Possible
Im possible
P ossible
Im possible
S ending
status
c
(Response send time after calling [ENQ] receive) + (Interval time)
d
Response send time after BCC send
e
(Response send time after acknowledgment [ACK] r (Interval time) or
(Response send time after negative acknowledge [NAK] r (Interval time)
z
Selecting procedure
S
T
X
B
C
C
A
C
K
N
A
K
or
… … …
c
d
H ost
com puter
R E X-F 9000
S end
data
(P os s ible/
Im pos s ible)
S ending
status
S ending
status
S end
data
(P os s ible/
Im pos s ible)
P ossible
Im possible
P ossible
Im possible
c
(Response send time after BCC receive) + (Interval time)
d
Response wait time after acknowledgment [ACK] send or
Response wait time after negative acknowledge [NAK] send