Omron CQM1H - PROGRAM Programming Manual page 436

Network Instructions
Examples
Executing RECV(98) just starts the data reception via the Communications
Unit. To check whether the reception was actually completed, verify that the
Network Instruction Enabled Flag (AR 0209) has gone from OFF to ON and
the Network Instruction Error Flag (AR 0208) is OFF. The reception process-
ing is completed when END(01) is executed.
A response is required with RECV(098) because the response contains the
data being received, so set bit 13 of C+1 to "0" to indicate that a response is
required. If the response hasn't been received within the response monitoring
time set in C+4, the request for data transfer will be retransmitted until a
response is received or the specified number of retries (up to 15) is reached.
If the Network Instruction Enabled Flag (AR 0209) is OFF when RECV(98) is
executed, the instruction will be treated as NOP(00) and won't be executed.
An error will occur and the Error Flag will be turned ON.
If the Network Instruction Enabled Flag (AR 0209) is ON when RECV(98) is
executed, the Network Instruction Error Flag (AR 0208) and Network Instruc-
tion Enabled Flag (AR 0209) will be turned OFF, the Network Instruction Com-
pletion Code will be set to 00, and the data will be received from the other
node.
Only one network instruction may be executed at one time. To ensure that a
second network instruction isn't executed until the first is completed, program
the Network Instruction Enabled Flag (AR 0209) as a normally open condi-
tion.
Never change the control data (C through C+3) while data is being received
and the Network Instruction Enabled Flag is OFF.
Noise and other factors can cause the request for transfer or response to be
corrupted or lost, so we recommend setting the number of retries to a non-
zero value which will cause RECV(98) to be executed again if the response is
not received within the response monitoring time.
Indirect addressing can be used for the source beginning word (S) when
receiving data from PCs that have larger data areas than the CQM1H such as
the CS1-series or CV-series PCs. Indirect addressing can also be used to
change the source beginning word to suit the circumstances.
Indirect Source Beginning Word Designations
S is used to specify the source beginning word when indirect specification is
required. Use the same designations as those used for the destination begin-
ning word for SEND(90).
When IR 00000 and AR 0209 (the Network Instruction Enabled Flag) are ON
in the following example, the data in ten words from DM 0100 to DM 0109 in
node number 3 in the local network is received and written to the ten words
from DM 0200 to DM 0209. The request for data transfer will be retransmitted
up to 3 times if a response is not received within ten seconds.
Section 5-29
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