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1010
Serial Communications Instructions
Section 3-24
If ER signal control is specified in C, bit 15 of S will be used as the ER signal.
If RS and ER signal control is specified in C, bit 15 of S will be used as the RS
signal and bit 14 of S will be used as the ER signal.
TXDU(256) uses a logical port (because it sends an internal FINS command)
to output a send sequence command to the Serial Communications Unit (ver-
sion number 1.2 or later). Since SEND(090), RECV(098), CMND(490),
PMCR(260), and RXDU(255) also use logical ports 0 to 7, TXDU(256) cannot
be executed for a logical port if that logical port is already being used by one
of those instructions or another TXDU(256) instruction.
To ensure that TXDU(256) is not executed while the logical port is busy, pro-
gram the port’s Communications Port Enabled Flag (A20200 to A20207) as a
normally open condition.
TXDU(256) can not be executed while the TXDU Instruction Executing Flag
(bit 5 of n+9 or n+19, where n = CIO 1500 + 25
×
unit number) is ON. To
ensure that another TXDU(256) is not executed for the port before the first
TXDU(256) is completed, program the port’s TXDU Instruction Executing Flag
as a normally closed condition.
An error will occur and the Error Flag will turn ON in the following cases.
• The Communications Port Enabled Flag for the specified logical port is
OFF when TXDU(256) is executed.
• The value of C is not within range.
• The value for N is not between 0000 and 0100 hex.
Note
Depending on the external device, it might be necessary to set a send delay
when sending data with TXDU(256). It a send delay is required, set or adjust
the delay time in the allocated DM Setup Area.
Related Flags and Words
The following PLC Setup settings and Auxiliary Area flag can be used as
required when executing TXD(236).
DM Setup Area Settings
(m = 100
×
unit number)
CPU Unit
TXDU
TXDU
Setup Area word
Bit
Name
Settings
Port 1
Port 2
m+2
m+12
15
No-protocol Mode Send
Delay Specifier
0: Default (0 ms)
1: Use delay in bits 1 to 14.
0 to 14
No-protocol Mode Send
Delay Time
0000 to 7530 hex
0 to 300,000 ms decimal
(in 10-ms units)
Summary of Contents for SYSMAC CS1D-CPU**
Page 3: ...iv...
Page 29: ...xxx...
Page 185: ...146 List of Instructions by Function Code Section 2 4...
Page 1389: ...1350 CJ series Instruction Execution Times and Number of Steps Section 4 2...
Page 1390: ...1351 Appendix A ASCII Code Table ASCII SP Four leftmost bits Four rightmost bits...
Page 1391: ...1352 ASCII Code Table Appendix A...