Mitsubishi Electric MELSEC FX Series - Allocation of Buffer Memories (Bfms); BFM List

FX communication
FX
2N
-232IF 10
10-2
10.2 Allocation of Buffer Memories (BFM’s)
The RS-232C interface block FX
2N
-232IF(232IF) transmits data with the programmable controller
via buffer memories BFMs (16-bit RAM memories) in the 232IF.
FNC78 (FROM) and FNC79 (TO) instructions are used to read and write the buffer memories.
10.2.1 BFM List
Note : “W : For write” can be used for read also. Undefined BFM Nos. are not allowed to be used
in program.
*1 : Spare buffers used in the interlink connection mode.
BFM
No.
Name Setting range Initial value
R:For read
W:For
write
#0
Communication format

0087H W
#1
Command

0W
#2
Receive upper limit byte count
1 to 512 (when data length is 16
bits)
1 to 256 (when data length is 8
bits)
“0” is treated as “512” or “256”.
0W
#3
Receive time-out time
1 to 32,767 (X10 ms)
“0” eliminates time-out time.
0W
#4
#5
Send header, lower 2 bytes
Send header, upper 2 bytes
4 bytes max., zero suppression
0 (no header)
0
W
#6
#7
Send terminator, lower 2 bytes
Send terminator, upper 2 bytes
4 bytes max., zero suppression
0 (no
terminator)
0
W
#8
#9
Receive header, lower 2 bytes
Receive header, upper 2 bytes
4 bytes max., zero suppression
0 (no header)
0
W
#10
#11
Receive terminator, lower 2
bytes
Receive terminator, upper 2
bytes
4 bytes max., zero suppression
0 (no
terminator)
0
W
#12
Receive suspension waiting
time (in interlink connection)
0 to 32,327 (X10 ms) 0 W
#13
Number of remaining send
data
0 to 512 (when data length is 16
bits)
0 to 256 (when data length is 8
bits)
0R
#14
Number of receive buffers 0 to 256 + 15 *1 0 R
#15
Send sum result

0R
#16
Receive sum result

0R