Rockwell Automation 1771-IS 5V DC INPUT MOD - Manual (Page 42)

Programming and Operation
Chapter 3
3-23
NOTES:
B001:0010
15
U
B002:0000
00
T0001
15
L
B002:0000
00
EN
DN
CNTL
12
CNTL
15
B002:0000
ER
CNTL
13
00
BLOCK XFER DONE
T0001
/
TE
T0001
17
TD
T0001
15
PLC–3 Block Transfer
b) Timer allows at least 20ms between block transfers.
a) Module located in rack 1, module group 2, slot 1.
TIMER DONE
BTR
BLOCK XFER READ
RACK :
GROUP :
MODULE:
DATA:
001
2
1 = HIGH
FD002:0012
LENGTH:
CNTL: 3
FB001:0010
TON
TIMER ON T0001
0.01 SECOND
TP = 2
TA = 0
Diagnostics
Bit 12 of the block transfer diagnostic word is the communication fault
bit. A communication fault can be caused either by cycling power to the
processor, by a break in I/O communications or by excessive electrical
noise radiating into the I/O communication cable. This bit will go ON if
the transfer is aborted. The I/O communication cable and system
grounding should be checked thoroughly in accordance with grounding
and shielding recommendations presented in the processor Assembly and
Installation Manual. This bit can be reset only by cycling power to the
module.
Data Buffering
Data that is block transferred to the data table should be buffered before it
is used to guard against the manipulation of invalid data by subsequent
user program instructions.