User Manual

5–3 Module Status and Input Data
Table 5.B provides bit/word descriptions for the block transfer read
instruction returned by the 1771-VHSC module to the processor.
Table 5.B
Bit/W
ord Description for the VHSC Module (1771VHSC)
Word Bit Definition
Bit 00
Powerup bit indicates whether a successful BTW with valid data has
occurred since powerup, or since last switched from Program to Run
mode.
Bit = 0  A successful BTW has occurred
Bit = 1  A successful BTW has not occurred
Word 1
Bits 0103
Not used
Bits 0407
New data bits. Indicates that a store register (BTR words 1118) has
been updated. These bits are reset by a 0 to 1 transition of the new
data acknowledge bits in BTW word 1, bits 47. Bit 04 corresponds to
counter 0, bit 05 to counter 1, etc.
Bits 0815
(Bits 1017)
Diagnostic byte. Always in BCD. This byte indicates the number of the
first word in the BTW file that was incorrect. Refer to chapter 7 for
other diagnostic error codes returned by the module.
Bits 0007
Status bits for outputs. Bit 00 corresponds to output 0, bit 01 to
counter 2, etc.
Bit = 0  output OFF
Bit = 1  output ON
Word 2
Bits 0811
(Bits 1012)
State of gate/reset input. Bit 08 (10) corresponds to counter 0,
bit 09 (11) to counter 1, etc.
Bit = 0  gate input inactive
Bit = 1  gate input active
Bits 1215
(Bits 1317)
Not used
Word 3
Contains the most significant digit for counter 0. The allowable range
is 0999.
Word 4
Contains the least significant digit for counter 0. The allowable range
is 0999.
Word 5
Contains the most significant digit for counter 1. The allowable range
is 0999.
Word 6
Contains the least significant digit for counter 1. The allowable range
is 0999.
Word 7
Contains the most significant digit for counter 2. The allowable range
is 0999.
Word 8
Contains the least significant digit for counter 2. The allowable range
is 0999.
Word 9
Contains the most significant digit for counter 3. The allowable range
is 0999.
Word 10
Contains the least significant digit for counter 3. The allowable range
is 0999.
Words 11
Counter 0 Store count values MSD (range 0999) in encoder/counter
mode; or frequency value MSD (range 0500) in rate measurement or
period/rate mode
Bit/Word Description for
Block Transfer Read