User manual

Chapter 3 Block Transfer Format
19
20 Gear Drive, Plymouth Ind. Park, Terryville, CT 06786
Tel: [phone] Fax: [phone]
Block Transfer Definition
Block Transfers are used by most intelligent I/O cards. Block Transfers move a block of up
to sixty-four words over the backplane at one time. This transfer will occur only when the rung
containing the Block Transfer instruction in your ladder logic program becomes true. Block
Transfer Read instructions transfer data from the module to the processor. Block Transfer Write
instructions transfer data from the processor to the module. The advantage of Block Transfers is
that both the position and tachometer data are transferred at one time.
Block Transfer Read Format
The PLC accepts four 16 bit words from the module when a Block Transfer Read instruction
accesses the module. The order and format of the words is shown in Figure 3.1.
The position data is divided into two words. For example if the position is 38,864 counts, the
first three digits (038) are in Word 1, the last three digits (864) are in Word 2. Tachometer data
is always transferred in binary format in Word 3.
Fault Bits
T
-
Transducer Fault, Bit 15 -
When these four bits (MSB in word 0 - 3) are set, a transducer fault
has occurred and is indicated with a blinking red LED on the front panel. The fault will clear
itself when a working transducer is properly attached to the 1761H module. Position and
tachometer data are set to zero during this fault. Therefore the values in words 1 thorough 3
equal -32,768 (8000h).
R
-
Reference Error, Bit 03 -
When this bit is set, a fault with the module has occurred and is
indicated with a blinking green LED on the front panel. The fault will clear itself when a
working transducer is attached to the module. If the error still exists, the module needs to be
returned to the AMCI for repair.
M
-
Module Fault, Bit 02 -
When this bit is set, the nvRAM memory is corrupted and is indicated
with a red LED on the front panel. Cycle power to the module. If the fault still exists, the module
needs to be returned to AMCI for repair.
C
-
Invalid Full Scale Count Parameter, Bit 01 -
When this bit is set, the count is outside the
range of 2 to (4096 * Number of Turns) for AMCI transducers or 2 to (1024 * Number of Turns)
for Autotech transducers.
N
-
Invalid Number of Turns Parameter, Bit 00 -
When this bit is set, the Number of Turns is not
valid for the type of transducer selected by the J-2 Jumper. See Table 3.1 page 20 for parameters
and their ranges.
Word 1
Word 2
Word 3
Word 0
0
151413121110090807060504030201
Upper 3 Digits Position Data
Lower 3 Digits Position Data
11 Bit Tachometer Data
00
0000000000RMCNT
000T
000T
0000T
Figure 3.1 Block Transfer Read Format