Mpu Controller Board; I/O Expander Board - Siemens Moore 353 User Manual

Circuit Description

13.2 MPU CONTROLLER BOARD

The heart of the 353 is the powerful, microprocessor-based MPU Controller Board. The flexible software supports
reusable function blocks beneficial in solving a vast array of control strategies such as single loop, cascade and dual
loop.
The Controller Board assembly contains both analog and digital circuits. The analog circuitry operates in real time
while the microprocessor based digital circuitry operates at high speed under program control. The MPU
(microprocessor unit) contains a CPU32 core, System Integration Module (SIM), a queued SPI module (QSPI),
timer module and two general-purpose 8-bit ports. The MPU is capable of arithmetic, logical, and support circuit
control functions and interacts with surrounding on-board and off-board circuitry to control the internal operation of
the 353. The MPU Board also contains 16-bit RAM, 16-bit ROM, a 2-wire RS485 connection, and an RS232
connection.
The CPU32 communicates with the RAM, ROM and external communications boards via the SIM. All
communication between the MPU and the I/O, display and expander board is done via the QSPI. The QSPI is a
full-duplex, synchronous serial interface with a queue for receive and transmit data. Communication consists of
timing, control, data, and sequencing information.
The Controller Board has three analog inputs, 3 digital inputs, 2 analog outputs and 2 digital outputs. The
configuration in use determines the active inputs and outputs. For example, Factory Configured Option FCO101 is
configured to accept one analog input for the process signal and one analog output for the valve signal. The two
analog outputs are 4 to 20 mA current sources with shutdown control for use in redundant control systems. The two
digital outputs are open collector devices with over-voltage protection.
Two serial ports are available for bi-directional asynchronous communications. Terminals NCA and NCB provide
an RS485 connection for LIL or Modbus network communications. An MMJ-11 connector on the underside of the
Display Assembly provides an RS232 connection for creating and editing configurations using the optional PC-
Based Graphical Configuration Utility. Since both ports are independent UARTs, communications with one serial
port will not interfere with communications to the other. Parameters in the STATN function block allow setting of
the Modbus baud rate and transmission characteristic for the Display Assembly MMJ-11 configuration port and
LIL/Modbus terminals NCA/NCB. (See STATN-Station Parameters in Section 3.) Additional information on
Modbus network communications and data mapping can be found in Section 6 and Section 7.
The RS-232 connection uses a DEC MMJ connector with the following six connections:
•
RTS - Handshaking output from MPU
•
TXD - Data output from MPU
•
Common
•
Common
•
RXD - Data input to MPU
•
CTS - Handshaking input to MPU
The on-board Power Supply circuit provides the power sources necessary for system power, internal analog output
power and transmitter power. Transmitter power is +26 Vdc at 0.125 amperes, to power up six process transmitters.

13.3 I/O EXPANDER BOARD

The I/O Expander Board communicates with the Controller Board and contains hardware that increases station
capability. Additional direct connected I/O includes two isolated universal analog inputs with thermocouple, RTD,
resistance, slidewire, mA and voltage conversions, two additional digital inputs that can be used as discrete or
frequency inputs, an additional analog output and two relay outputs. All calibration data for the Expander Board is
stored in the board's nonvolatile EEPROM making recalibration unnecessary when interchanging Expander and
Controller Boards.
Expander circuitry operates under the control of the MPU-based Controller Board, and like the Controller Board, it
contains both analog and digital circuitry. The analog circuitry operates in real time while the digital circuitry
operates at high speed under program control.
13-2
UM353-1
March 2003