Hitachi EH-150 Series, Applications Manual

Page: 58 / 194

Chapter6 Communication Mode
6 - 16
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6.2.5 Receive data
Received data is divided into packets according to the message composition registered in initial setting, and is
stored in a receiving buffer. The number of effective receiving packets is displayed on an input register (for port 1:
WXus2, and for port 2: WXus3).
CPU module reads one packet from the receiving buffer of EH-SIO by executing TRNS 9 command (data receive
command). Only one packet can be read by one command execution. The packets are read in the order in which
they were stored in the receiving buffer. In addition, when an error occurs at the time of data receiving, error
information is counted as one packet.

s parameter
Data receiving command from CPU module to EH-SIO is H0010
In addition, although the sending data area, specified by s+9 and s+A, is not used in this command. Please set
dummy parameters in s+9 to s+A.
Figure 6.15 s parameter format (Free protocol / Data receiving)

Execution of data read
Please turn on command execution flag (t+0) after storing the parameter required for s parameter.

End of data read
(1) Receiving data are read
When receiving data are read properly, completion flag (t+1) goes on, and H0010 is set to return code area. The
read data are stored according to s parameter s+B and s+D. (The number of data [bytes] is stored at the top of the
receiving data area.)
Figure 6.16 Receiving data area format (Free protocol)
When read data exceed the receiving area size, surplus data part is ignored.
System area ( 6 words )
Return code
H0010 (Command)
s
s+7
s+8
s+9
s+B
s+D
Set by user
Size of receiving data area
Top I/O address of
receiving data area
Command timeout time
Top I/O address of
sending data area
Dummy parameter
Number of read data (bytes)
1st byte
S
ize
o
f
re
ce
iv
in
g
d
ata are
a
…
2nd byte
3rd byte 4th byte
(n-1)
th
byte n
th
byte
H00 at the time of
odd-byte reception.