User`s manual

FX communication
Commands 8
8-17
8
3 ) On-demand request time chart.
• When the computer is transmitting data
a ) When on-demand is requested, the on-demand execution signal (special M8127) is
immediately turned on.
b ) Transmission of on-demand data is forced to wait until completion of reception of
command data (ENQ-) from the computer.
c ) Transmission of response data (STX-) to command data (ENQ-) is forced to wait until
completion of transmission of on-demand data.
• When the computer is receiving data
a ) When on-demand is requested, the on-demand execution signal (special M8127) is
immediately turned on.
b ) Transmission of on-demand data is forced to wait until completion of transmission of
response data (STX-) to the command data (ENQ-) from the computer.
c ) Transmission of response data (ACK-) from the computer to the transmission of response
data (STX-) from the programmable controller should be done after completion of
reception of on-demand data.
Computer
Programmable
controller
E
N
Q
S
T
X
A
C
K
On-demand
execution
flag M8127
Start on-demand,
writing of the on-
demand data length
b) On-demand data
a)
c)
Programmable
controller
Computer
Programmable
controller
E
N
Q
S
T
X
A
C
K
On-demand
execution
flag M8127
Start on-demand,
writing of the on-
demand data length
On-demand data
a)
c)
b)
Programmable
controller