User manual

11
Publication 1738-SG001B-EN-P
ArmorPoint I/O
DDiiggiittaall II//OO MMoodduulleess
Choose digital I/O modules when you need:
The 1738 digital I/O modules support:
y a wide variety of voltage interface capabilities
y isolated and non-isolated module types
y point-level output fault states
y choice of direct-connect or rack-optimized communications
y field-side diagnostics on select modules
Connector types are indicated by the catalog number. For example, the 1738-IB2M12 has
an M12 connector.
y Input modules. An input module responds to an input signal in the following manner:
- Input filtering limits the effect of voltage transients caused by contact bounce and/or
electrical noise. If not filtered, voltage transients could produce false data. All input
modules use input filtering.
Optical isolation shields logic circuits from possible damage due to electrical
transients.
- Logic circuits process the signal.
- An input LED turns on or off indicating the status of the corresponding input device.
y Output modules. An output module controls the output signal in the following manner:
- Logic circuits determine the output status.
- An output LED indicates the status of the output signal.
- Optical isolation separates module logic and bus circuits from field power.
- The output driver turns the corresponding output on or off.
y Surge suppression. Most output modules have built-in surge suppression to reduce
the effects of high-voltage transients. However, we recommend that you use an
additional suppression device if an output is being used to control inductive devices,
such as:
- Relays
- Motor starters
- Solenoids
- Motors
Additional suppression is especially important if your inductive device is in series with
or parallel to hard contacts, such as:
- Push buttons
- Selector switches