How to install GE Series 90-70 Genius Bus Controller?

GE Series 90–70 Genius Bus Controller

Product Overview

Series 90-70 Genius Bus Controller (model IC697BEM731) is an interface module used to connect Genius I/O serial bus with Series 90-70 PLC. It supports communication with Genius I/O blocks, remote I/O sites, handheld monitors, and other devices, and can achieve functions such as data transmission, diagnosis, distributed control, and redundancy. It follows multiple international standards and is suitable for various automation control scenarios.

Core functions and system composition

System Overview

The Series 90-70 PLC bus controller (product number IC697BEM731) is used to connect the Genius I/O serial bus to the Series 90-70 PLC.

The devices that Genius bus can serve include:

Genius module: Provides interfaces with various discrete, analog, and special-purpose field devices, with advanced diagnostic capabilities and many software configurable features.

Remote nodes: Series 90-70 I/O racks connected to the bus through remote I/O scanner modules, each remote node can contain any combination of discrete and analog I/O modules, providing up to 128 bytes of input data and 128 bytes of output data.

Handheld monitor: can be used as a portable device or permanently installed, providing a convenient operator interface for module settings, data monitoring, and diagnostics.

Multiple hosts: used for communication through datagrams and global data.

Bus can achieve various functions, such as enhancing I/O control through communication commands in the program, only used for I/O control, dedicated for CPU communication, and can also develop more complex systems.

Number of bus controllers

Series 90-70 PLC systems with CPU versions 3.0 and higher can contain up to 31 bus controllers.

Early CPU versions could accommodate up to 16 bus controllers.

In some redundant system configurations, there are fewer available bus controllers, as detailed in Chapter 6.

I/O devices on the bus

The I/O devices on the bus can be Genius I/O modules or standard Series 90-70 I/O modules in one or more remote nodes.

The total number of I/O circuits that a Genius bus can serve depends on the type of I/O device used and the available memory in the CPU.

Memory requirements for Genius module:

For% I and% Q memory, the size shown is in bits; For% AI and% AQ memory, the size shown is in words.

Different types of modules (such as 115 VAC grouped I/O modules, 115 VAC isolated I/O modules, etc.) have different maximum memory requirements.

Many Genius I/O modules have both inputs and outputs on the same module. Modules configured as both inputs and outputs in Logicmaster 90 software will occupy the same reference in% I and% Q memory. Unused references cannot be allocated to other inputs or outputs and should not be used in applications.

Memory requirements for remote nodes: A 90-70 remote I/O scanner (IC697BEM733) and the modules it serves form a remote node on the Genius bus. The remote node can include any combination of Series 90-70 discrete and analog input-output modules, with a maximum total of 128 bytes of input and 128 bytes of output (8 discrete points represent one byte, and 1 analog channel uses 2 bytes).

Bus controller description

The bus controller is a standard rack mounted Series 90-70 PLC module.

Status LED: The front LED indicates its operating status, the top two LEDs should light up during normal operation, and the bottom LED is not in use.

Module OK: Displays the status of the bus controller and flashes during power on diagnostics.

Channel OK: Displays the status of the bus. It lights up steadily when the bus is running normally, flashes intermittently when there are bus errors, goes off when the bus is faulty, and also goes off when no configuration is received from the PLC CPU.

Handheld monitor connector: The handheld monitor connector on the bus controller panel is used to connect a handheld monitor. For the IC697BEM931 bus controller, if there is a lower HHM connector, it is not used. Except for the allocation of I/O module device numbers, all handheld monitor functions can be executed through HHM connected to the bus controller. It is recommended to use IC660HHM501C (or higher version) handheld monitor to ensure normal operation with Series 90-70 PLC.

Terminal components: The serial bus and shielded wire are connected to the removable terminal block on the front of the bus controller. For the IC697BEM931 bus controller, only the upper three terminals are used. To remove terminal components without interfering with bus continuity, jumper wires are required, as detailed in Chapter 2.

Genius bus

Bus type: Daisy chained bus cable; Single twisted pair cable with shielding or Twinax. Fiber optic cables and modems can also be used.

Bus terminal: Connect 75, 100, 120, or 150 ohm resistors at both ends of the electrical bus cable.

Baud rate: configurable, standard 153.6 Kbaud, extended 153.6 Kbaud, 76.8 Kbaud, or 38.4 Kbaud.

Maximum bus length: 7500 feet at 38.4 Kbaud, 4500 feet at 76.8 Kbaud, 3500 feet at 153.6 Kbaud expansion, and 2000 feet at standard 153.6 Kbaud. The maximum length at each baud rate also depends on the cable type. Chapter 2 provides a complete list of cable types, displaying the corresponding bus length and baud rate. Using fiber optic cable segments with modems can achieve longer bus lengths.

Maximum number of devices: 32 devices at 153.6 Kbaud standard, 153.6 Kbaud extension, or 76.8 Kbaud; At 38.4 Kbaud, there are 16 devices, including a bus controller, and usually one handheld monitor.

Data encoding: Each bit is encoded as three double pulses, and the receiver performs a majority vote to correct any single double pulse error. Double pulse is an AC code consisting of a positive voltage followed by a negative voltage offset, which is sampled separately to suppress low-frequency and high-frequency interference.

Modulation technique: Frequency Shift Keying (FSK) 0 to 460.8 KHz maximum (153.6 Kilobaud).

Isolation: 2000V high voltage, 1500V transient common mode suppression.

Signal to noise ratio: 60 dB.

Bus controller operation

The bus controller handles all data transfers between the PLC and devices on the bus, requiring the docking of two completely independent and asynchronous activities: Genius bus scanning (the communication cycle between devices on the bus, following the order of bus addresses 0-31) and CPU scanning (including the operation cycle of communication between the CPU and the bus controller).

The bus controller manages data transfer between the bus and CPU by maintaining two independent onboard RAM memories, one with the bus interface and the other with the CPU interface. The bus controller automatically transfers data between these two memories and provides data to the bus or CPU when needed.

Genius bus scan: Bus scan includes a complete cycle of "tokens" between devices on the bus, which may include other bus controllers or remote I/O scanners, as well as Genius modules. During bus scanning, the bus controller automatically performs operations such as receiving all input data sent by devices on the bus, broadcasting global data, updating outputs (if allowed), receiving any fault messages sent by devices on the bus and setting diagnostic status references for CPU use, and sending individual commands received from the CPU to the corresponding devices. The time required for communication tokens to be transmitted to all devices depends on the baud rate, the number and type of devices on the bus, and the usage of global data and datagram communication.

Input data from devices on the bus: Every time a module or remote I/O scanner has a communication token, the bus controller receives the input data they send (as this data is broadcast, it may be received by any other bus interface module running on the bus). The bus controller stores all received input data, and the CPU reads all discrete and analog inputs from the bus controller every time it scans (analog data is not multiplexed).

Output data from CPU: As the application program executes, the CPU sends output and any commands to the bus controller, which stores this data and transmits it on the bus every time it has a communication token. Unlike the input of broadcasting, the output is directed to the specific device that should receive them.

Diagnosis: Genius modules and other devices on the bus will automatically report faults, alarms, and certain other predefined conditions to the PLC. During any bus scan, only one diagnostic message can be sent. If a fault message has already been sent (by another device) during that scan, the device will save its diagnostic message to the next available bus scan. The bus controller stores any diagnostic messages received, and the Series 90-70 CPU automatically reads them. The Logicmaster 90-70 software can then be used to display the fault in the fault table and clear it from the programmer. For details, see Chapter 4. Genius handheld monitors can also be used for diagnosis and troubleshooting. In addition to the built-in diagnostic capabilities of Genius devices, the Logicmaster 90-70 application can also utilize other diagnostic mechanisms provided by the Series 90-70 PLC, such as system state references defined for Genius, fault and fault free contacts that can be used to detect faults and no fault conditions, and alarm contacts that can be used to indicate when simulated values reach specified alarm limits.

Datagrams

The Series 90-70 bus controller supports all Genius datagrams, including Read ID、Read ID Reply、Read Configuration、Read Configuration Reply、Write Configuration、Assign Monitor、Read Diagnostics、Read Diagnostics Reply、Write Point、Read Block I/O、Read Block I/O Reply、Report Fault、Pulse Test、Pulse Test Complete、Clear Circuit Fault、Clear All Circuit Faults、Switch BSM、Read Device、Read Device Reply、Write Device、Read Data、Read Data Reply、Write Data、Read Map、Read Map Reply、Write Map  Wait, each type of datagram has its specific description and function.

Global Data

Global data is automatically and repeatedly broadcasted by the bus controller. The Series 90-70 bus controller can send up to 128 bytes of global data per bus scan and receive up to 128 bytes of global data from each bus controller on the bus per bus scan.

Sending global data: Once configured (see Chapter 3), global data will be automatically broadcasted. Other bus controllers that receive global data sent by Series 90-70 PLCs will place it in different memory locations. For example, Series 90-70 PLCs will place it in the corresponding memory according to the configuration of the receiving bus controller, and Series 90-30 PLCs will place it in the% G memory location corresponding to the device number (16-23) of the Series 90-70 bus controller that sends data.

Receive global data: The bus controller can be configured to receive or ignore global data from any other bus controller, and the memory type and length of the incoming global data are also selected during configuration, as detailed in Chapter 3. Series 90-70 CPUs can place incoming global data in% I,% Q,% G,% R,% AI, or% AQ memory.

Operation and Diagnosis

1. Data transmission process

Bus scanning: The controller scans devices in a loop through token passing, receives input data, and broadcasts output; Synchronize data through onboard RAM during the CPU scanning cycle.

Communication Request (COMREQ): The operation is defined through a Command Block, supporting 16 types of commands (such as Pulse Test, Read/Write Configuration), and the Status Block returns the execution result (success/failure code).

2. Diagnostic function

Fault table: records circuit faults (such as disconnection, short circuit), module faults (such as memory errors), communication faults (such as full datagram queue), etc., which can be viewed or cleared through Logicmaster software.

Status reference: Provide system level fault signals (such as LOS_SOC, IOUFULL), support fault contact linkage control.

Advanced features

1. Distributed control and monitoring

Distributed control: Multiple CPUs control different devices by disabling outputs to avoid conflicts.

Data monitoring: Supports the Assigned Monitor mode, which specifies the device to receive additional fault reports through the Assign Monitor command.

2. Redundant system

Redundancy mode: Dual bus (same PLC or dual PLC), redundant controller (Hot Standby/Duplex mode), ensuring seamless switching in case of bus failure.

Configuration example: Provide configuration steps for 6 typical scenarios (such as single PLC dual bus, dual PLC redundant control).