Allen-Bradley 1734-OB2, User Manual, Page: 110 / 221

Rockwell Automation Publication 1734-UM001E-EN-P - July 2013
112 POINT I/O Module Data
Channel Status can be read individually using RSNetWorx software or by reading
the Channel Status Byte in the Module Produce Assembly.
• Channel Fault Bit -This general channel health bit (Channel Status Bit 0)
indicates that the module is operating with or without faults. If any alarms
or faults are detected, this bit is set.
• Calibration Status Bit - This status bit (Channel Status Bit 1) is set when
the channel is in Calibration mode. At Begin Calibration, the module is
put into Calibration mode. This bit does not get set until the Output Low
Reference or Output High Reference commands are sent.
Do not confuse
this bit with the Bad Calibration Status bit, which is set if the module is
not
calibrated.
•
Low Clamp Status Bit - This status bit (Channel Status Bit 2) is set when
the output data is clamped to it’s minimum level. The default value is
-32,768 counts. Low Clamp Status can be read on a per-channel basis or
by reading the Module Produce Assembly.
• High Clamp Status Bit - This status bit (Channel Status Bit 3) is set when
the output data is clamped to its maximum level. The default value is
32,767 counts. High Clamp Status can be read on a per channel basis or by
reading the Module Produce Assembly.
Open-wire Detection (1734-OE2C only)
This condition has no unique status bit, but if an open-wire condition exists, the
general Channel Status bit is set. The module can’t determine what the condition
is: open wire or loss of field power. The Channel indicators blinks red.
Power Fail Detection (1734-OE2V only)
This condition has no unique status bit, but if a power failure condition exists,
the general Channel Status bit is set. The Channel indicators goes to solid red.
Low and High Clamps
The clamps define the maximum and minimum values of the output. These
default to the following with the data scaled:
• -32,768 counts (0 or 4 mA) and +32,767 counts (21 mA) for the
1734-OE2C module
•
-32,768 counts (0 or -10V) and +32,767 counts (+10V) for the
1734-OE2V module
Each clamp can be set individually and on a per-channel basis. When the output
value reaches clamp value, a status bit is set, indicating the output has been
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Not Used High
Clamp Low
Clamp CAL
Mode Channel
Fault