Rockwell Automation 1769-OF4 Compact Analog Output Module - Manual (Page 32)

32 Publication 1769-UM020A-EN-P - December 2009
Chapter 3 Module Data, Status, and Channel Configuration
Under-range (low clamp) Status Bits (U0…U3)
Under-range (low clamp) bits for output channels 0…3 are contained
in Word 0, bits 9, 11, 13, and 15. When set (1), these bits indicate an
output value sent to the module is less than or equal to the
user-configured low clamp value for the output channel. The module
clamps the analog output signal at the low clamp value. These bits are
automatically reset (0) by the module when the low clamp condition
clears, unless the channel’s clamp status bits are latched. The module’s
output signals always return to normal operation when directed to
values allowed by the high clamp and low clamp settings. If the
channel’s clamp status bits are latched, a set (1) low clamp status bit
clears via the corresponding Cancel Low Clamp Latch bit in your
output data file.
Output Data File The output data file lets you write analog output data and unlatch
command data to the module with the control program and bit access.
The data table structure is shown in the table below. For each
module, slot x, words 0…3 in the output data file contain the digital
values of the data to be converted to analog signals by the module
outputs. The most significant bit (MSB) is the sign bit, in two’s
complement format. ‘Nu’ indicates not used with the bit set to zero.
Cancel Clamp Alarm Latch Control Bits (CLO0…CLO3 and
CHO0…CHO3)
These bits are written during Run mode to cancel any latched low and
high clamp status bits. The status bit is unlatched on a low to high
transition (0 to 1) of the unlatch bit if the clamp condition no longer
exists. If the clamp condition persists, then the low to high transition
of the unlatch bit has no effect. You need to continue to toggle the
unlatch bit until verification from the appropriate output-channel
status word that the clamp status bit has cleared (0).
Word/
Bit 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Word 0 SGN Analog Output Data Channel 0
Word 1 SGN Analog Output Data Channel 1
Word 2 SGN Analog Output Data Channel 2
Word 3 SGN Analog Output Data Channel 3
Word 4 NU NU NU NU NU NU NU NU CLO3 CH O3 CLO2 CH O2 CLO1 CH O1 CLO0 CH O0