Seriplex - an Introduction

The traditional approach to I/O is to use a centralized PLC and I/O rack and route cable or wire to the field I/O for communication and control. Cable and routing start-up costs for such a system are normally quite large, and maintenance and troubleshooting difficult. An extension of this approach provides for locating remote I/O racks in defined areas more closely situated to the actual field I/O. Though a more distributed approach than the previous method, it can still require a substantial outlay for cabling and conduit, and frequently requires the addition of a communications network to transmit data between the processor(s) and remote I/O racks.

In a Seriplex system, the concept of I/O distribution is carried to the I/O point level. The simple cabling and the cost savings realized allow more flexibility in sensor/actuator deployment for applications such as pilot program design and temporary plant floor configuration. Each Seriplex I/O module contains a patented chip designed to handle communications, logic, and control. This fully distributed approach allows Seriplex networks to operate in either a host controlled or peer-to-peer mode.

Available Seriplex products include AC and DC digital I/O, analog inputs and outputs, and peripheral devices from several manufacturers which offer embedded Seriplex support.

The Niobrara SPXM

The SPXM interfaces to the PLC through rack addressed registers. Register 1 is the SPXM's configuration register; in this register the bus length, multiplexed I/O information, clock rate, and Seriplex mode are established. The other rack-addressed registers are mapped to Seriplex peripherals. The SPXM supports any length Seriplex bus up to 256 bits in multiples of 16. It also supports multiplexing of 4, 8, 12, or 16 channels deep by up to 240 bits wide in multiples of 16 bits.

Power for the SPXM is drawn from the SY/MAX bus. When the SPXM serves as the interface for a Seriplex network, no clock module is needed; the SPXM supplies the Seriplex clock and also serves as the source of pull-up current for the Seriplex data line.

The Seriplex I/O network is connected to the SPXM via a 9-pin D-subminiature connector on the module's front panel. LEDs also located on the front panel indicate power on, run, bus undervoltage, and bus fault. The SPXM can detect undervoltage, clock shorted l ow, clock shorted high, data shorted low, data shorted high, and external clock source error conditions. SPXMSW, NR&D's configuration software, is supplied with the module as an aid to determining the SPXM's proper configuration.

Use the SPXM to:

SPECIFICATIONS:

Dimensions: Standard SY/MAX register module. 1.5" wide by 13" tall by 6.5" deep. Approximately four pounds net. Rugged welded steel enclosure with baked on finish. Seriplex connector and indicators are front mounted; SY/MAX bus card edge connector on the back.

Power Requirements: From SY/MAX bus, 5 volts, 500mA. From Seriplex, 12 or 24 volts in accordance with Seriplex standards.

Seriplex Port: 9-pin male D-subminiature connector with screw locks. For use with standard four conductor Seriplex cable. Optically isolated.

Indicators: Front panel LED indicators for Power, Run, Undervoltage, and Fault.

Setup Registers: Configuration contained in rack-addressed register 1; loaded by the user's ladder program.

PLC Interface: Rack-addressed registers

Seriplex Interface: Up to 255 discrete I/O points or 240 16-bit multiplexed words.

ORDERING INFORMATION

SPXM Seriplex Interface Module