Emerson FB1200 - Digital Outputs

Emerson FB1200 Flow Computer Instruction Manual
D301782X012
March 2019
64 I/O Configuration and Wiring
3.4 Digital Outputs
Depending upon how you ordered it, the flow computer includes two or six channels you can
configure as digital outputs (DO), digital inputs (DI) or pulse inputs (PI).
Note
When using a digital output to drive an inductive load (such as a relay coil), place a suppression diode
across the load. This protects the DO from the reverse Electro-Motive Force (EMF) spike generated
when the inductive load is switched off.
When configured as digital outputs, the channels have the following characteristics:
Table 3-4: Digital Output Characteristics
Type
Number Supported
Characteristics
Digital
Output
(DO)
0 to 6 as follows:
▪
1 or 2 non-isolated channels on CPU
board (PI/DI/DO1 and PI/DI/DO2). Two
always present; you can configure one,
both, or neither as DOs.
▪
1 to 4 additional non-isolated channels
on optional 6-channel expansion I/O
board (PI/DI/DO3 through PI/DI/DO6).
If present you can configure one, two,
three, four or none as DOs.
▪
DO is a low side switch that sinks
current to ground
▪
Current rating of 500 mA
▪
Maximum operating frequency of 50
Hz
▪
Pulse off/on time can be configurable
with a 31 ms minimum on time and a
31 ms minimum off time
▪
Can be configured in software with an
output state for initial power-up and
in the case of a CPU failure
▪
Software configurable failure mode of
fail open, fail closed, or hold last state
▪
When a channel is configured as a DO
it cannot be used as a DI or PI channel