Function of Control/Status Bits
Chapter 6
619
Command Word One
Bit
Function
Status
17
Initialization
0 = Reset
1 = Up to four initialization words will follow
command words CW1 CW2
16
Write Data Available
Toggled status, CW(16)
≠
SW(16), tells
module that transfer contains new data
15
Read Data Acknowledge
Toggled status, CW(15) = SW(15), tells
module that processor received previous
transfer
14
Incomplete String
0 = Reset
1 = Used for installation debugging, not for
normal operation
13
Port Disable
0 = Reset
1 = Disables communication thru the interface
port
12
Self Diagnostics
0 = Reset
1 = Enables self diagnostics. You must re
initialize the module
11, 10
Not used
Set them to zero
07
Resets Powerup and
Handshaking
0 = Reset
1 = Resets SW1 (07) Initialization bit,
SW1(15) Read data available bit, and
SW1(16) Write data acknowledge bit
06, 05, 04 Not used
Set them to zero
03
Resets Input Buffer
Full Bit
0 = Reset
1 = Resets SW1(03) buffer full
02
Not used
Set it to zero
01
Reserved for future
use
Reset this bit to zero
00
Reserved for future
use
Reset this bit to zero
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