Watlow Electric Revision 5 - Manual (Page 44)

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Direct [Cool]. The outputs are 5vdc at 16ma maximum and are normally
used to switch optically-isolated solid-state relays (SSR's).
The alarm and status outputs include a global high and low deviation and a
watchdog timer which are set by the SYSTEM 32. If ANASOFT-32 is used
in the system computer, a global high and low process alarm output is set
from the system computer. These outputs are also 5vdc and are designed to
connect to SSR's.
The additional digital I/O are used by special versions of ANASOFT-32.
Eight digital outputs are available on the terminal strips, and the remaining
8 digital inputs and 16 digital outputs are provided on a 50 pin ribbon cable
connector. The pin configuration is compatible with standard I/O modules
such as Gordos PB24.
7.1.2 Communication
The type of communication interface is determined by the distance the 32
System will be from the host computer. The communications interface type
is set at the factory. RS-232 is recommended up to 50 feet although it can
be used up to 500 feet with special cables in low electrical noise
environments. For longer distances either the 20ma Current Loop (up to
5000 ft.), or the RS-485 (up to 10,000 ft.) is recommended. The 20ma
current loop is a dual twisted pair serial connection and RS-485 is 4 or 2
wire balanced line parallel connection.
7.1.3 Address and Option Switch
An 8-position dip switch on the PIOM provides for the address selection.
The addresses allow up to 16 SYSTEM 32 PIOM's to be on the same
communication line. It also allows selection of the baud rate of 2400 or
9600 as well as other communication parameters.
7.1.4 Terminal Blocks
Push on, screw locked terminal blocks are provided on each module for
connection of field wiring. The blocks are large enough for most types of
input wiring. The blocks can be removed to service the modules without
the need to remove the field wiring. The blocks also include temperature
stabilization to improve the reference junction compensation when
thermocouples are directly connected.
7.2 REED RELAY ANALOG INPUT MODULE -- A32-RRAIM
The RRAIM provides the connections for up to 16 analog inputs to the SYSTEM
32. Analog inputs are sequentially switched to a frequency [V/F] converter
powered by an isolated supply. The pulse output from this V/F passes through an
optical-isolator and to the PIOM where the pulses are counted and the readings are
determined. In addition to the analog inputs, two temperature sensors at each end
of the terminal blocks are measured for use as an electronic reference junction for
directly connected thermocouples.