GE IS200SSCAH2A Simplex Serial Communication Input/Output Terminal Board

The IS200SSCAH2A is a Simplex Serial Communication Input/Output Terminal Board designed by General Electric (GE) for its Mark VIe™ Control System. This board is the version within the SSCA series that features pluggable terminal blocks. Its primary function is to provide up to six serial communication channels, each independently configurable for RS-232C, RS-485, or RS-422 communication protocols, enabling data exchange between the control system and various external devices.

The core function of the IS200SSCAH2A board is to connect field devices (such as PLCs, smart instruments, drives, third-party controllers, etc.) to the Mark VIe control system via serial communication interfaces. The I/O pack plugs into the DC-62 pin connector on the board to achieve Ethernet communication with the Mark VIe controller, thereby integrating serial data into the control system.

The IS200SSCAH2A is the H2 version within the SSCA series, and its main feature lies in the terminal block design:

• SSCAH1: Features a permanently mounted 48-terminal terminal block.

• SSCAH2A: Features a right-angle header that accepts a range of commercially available pluggable terminal blocks, also providing 48 terminals.

This pluggable design greatly facilitates on-site wiring and maintenance. Users can select the appropriate terminal block type as needed, and when installing or replacing the board, there is no need to rewire; simply unplug the terminal block.

The board has a compact design, measuring 15.9 cm × 10.2 cm. It is DIN-rail mounted using a sheet metal carrier and plastic insulator mount. This assembly can also be bolted directly into a cabinet. The board utilizes surface-mount technology and operates within a temperature range of -30 to 65°C, making it suitable for industrial field environments.

Key features of the IS200SSCAH2A board include:

• Six Independent Serial Channels: Each channel can be independently configured for RS-232, RS-422, or RS-485.

• Pluggable Terminal Blocks: Facilitates on-site wiring and maintenance.

• Flexible Termination Resistor Configuration: Jumpers allow selection of 121 Ω termination resistors.

• Selectable RET Grounding Method: The RET line for each channel can be selected for resistive or capacitive grounding.

• ID Chip Identification: The JA connector on the board features an ID chip read by the I/O pack for identification.

• Software Configuration: Parameters such as communication protocols are configured via ToolboxST software.

  
  

II. Main Functions

The primary functions of the IS200SSCAH2A include, but are not limited to, the following:

1. Multi-Protocol Serial Communication

Each of the six independent channels on the IS200SSCAH2A board can be software-configured for one of three communication protocols:

• RS-232C: Point-to-point communication, suitable for short distances (up to 50 feet or 2500 pF capacitive load).

• RS-422: Differential communication, suitable for longer distances (up to 1000 feet), supporting full-duplex.

• RS-485: Differential communication, suitable for longer distances (up to 1000 feet), supporting half-duplex multi-drop connections (up to 8 nodes).

2. Pluggable Terminal Block Design

The IS200SSCAH2A features a right-angle header that accepts various commercially available pluggable terminal blocks, providing 48 terminals. The advantages of this design include:

• Easy Wiring: Wiring can be done offline and then the terminal block plugged into the board.

• Convenient Maintenance: When replacing the board, there is no need to rewire; simply unplug the terminal block and plug it into the new board.

• High Flexibility: Different types of terminal blocks (e.g., screw-type, spring-type) can be chosen as needed.

3. Termination Resistor Configuration

For RS-422 and RS-485 communication, termination resistors are required at both ends of the transmission line to match impedance and prevent signal reflections. The IS200SSCAH2A provides selectable termination resistors for each pair of signal lines per channel:

• Jumper JP#A: Controls the termination resistor between signals A and B (121 Ω, 1/2 W, 1%).

• Jumper JP#B: Controls the termination resistor between signals C and D (121 Ω, 1/2 W, 1%).

The default jumper position is open, with the termination resistor disconnected. When needed, the jumper can be set to the IN position to connect the resistor.

4. RET Grounding Method Selection

In RS-232C communication, it is often undesirable to have a hard ground of the RET signal path on both ends of a cable. The IS200SSCAH2A provides selectable grounding options for the RET line of each channel:

• Resistive Ground (RES): Grounded through a 100 Ω resistor (default position).

• Capacitive Ground (CAP): Grounded through a 0.01 uF capacitor in parallel with a 1 MΩ resistor.

If the connected device already has a hard ground on its RET line, the capacitive ground should be selected. If the connected device does not have a hard ground, the resistive ground should be selected.

5. Signal Assignment and Arrangement

The 48 terminals on the SSCAH2A are grouped by channel. Each channel uses 6 terminals in the order SCOM, A, B, C, D, RET. The terminal assignments for the six channels are as follows:

6. Hardware ID Identification

The JA connector on the board features a read-only ID chip storing the board's serial number, type, revision number, and connector location information. The I/O pack reads this information during initialization. If a mismatch is encountered, a hardware incompatibility fault is generated.

7. Software Configuration

Except for the termination resistors and RET grounding method, which are configured by hardware jumpers, all other parameters (such as communication protocol selection, baud rate, data bits, stop bits, parity, etc.) are configured via ToolboxST software.

III. System Applications

1. Application in Mark VIe Control System

The IS200SSCAH2A is a key terminal board for serial communication expansion within the Mark VIe control system. Its roles within the system include:

• Protocol Conversion: Converts serial communication protocols (RS-232, RS-422, RS-485) from field devices into data formats recognizable by the control system.

• Data Integration: Integrates data from serial devices into the Mark VIe control system via the I/O pack and Ethernet for centralized monitoring and control.

• Device Interface: Provides physical interfaces for various serial devices, including PLCs, smart instruments, drives, barcode scanners, and third-party controllers.

• Network Expansion: Via RS-485 multi-drop connections, up to 8 devices can be connected, expanding the I/O capability of the control system.

2. Differences from IS200SSCAH1A

The main difference between IS200SSCAH2A and IS200SSCAH1A lies in the terminal block design:

• IS200SSCAH1A: Features a permanently mounted 48-terminal terminal block; wiring is non-removable.

• IS200SSCAH2A: Features a right-angle header that accepts pluggable terminal blocks; wiring can be removed by unplugging the terminal block.

Advantages of the pluggable design:

• Wiring can be done before board installation, increasing installation efficiency.

• When replacing the board, no rewiring is needed; simply unplug the terminal block and plug it into the new board.

• Different brands or types of terminal blocks can be chosen as needed.

3. Typical Application Scenarios

• PLC Communication: Serial communication with various brands of PLCs to exchange control commands and status data.

• Smart Instrument Interface: Connecting smart meters, flow meters, analyzers, and other instruments to collect process data.

• Drive Control: Communicating with variable frequency drives, servo drives, etc., for motion control.

• Third-Party System Integration: Exchanging data with third-party control systems or SCADA systems.

• Commissioning and Maintenance: Acting as a temporary commissioning interface, connecting a computer running simulation software like MODSIM.

  
  

IV. Detailed Interface Description

1. Terminal Block Signal Definitions

The 48 terminals on the IS200SSCAH2A are grouped by channel. The signal definitions for each channel are as follows:

2. Terminal Assignment Table

3. Jumper Description

4. DC-62 Pin Connector

This connector is used to connect the I/O pack, enabling Ethernet communication with the Mark VIe controller. Refer to the relevant I/O pack documentation for specific pin assignments.

5. Shield Ground

SCOM terminals (37-48) must be connected to a suitable shield ground. Typically, the shield of the I/O cable should be grounded via an external mounting bracket and then connected to the board through the SCOM terminal.

V. Configuration and Wiring

1. Communication Protocol Configuration

The communication protocol is selected via ToolboxST software, requiring no hardware jumpers. Each channel can be independently configured for:

• RS-232C

• RS-422

• RS-485

2. Termination Resistor Configuration

Set the corresponding termination resistor jumpers according to the communication protocol and network topology:

3. RET Grounding Method Configuration

Set the corresponding RET grounding jumper according to whether the connected device has a hard-grounded RET:

4. RS-232C Wiring Example

Connecting SSCA Channel 1 to a third-party device (slave):

5. RS-485 Half-Duplex Wiring Example (Point-to-Point)

Connecting SSCA Channel 1 to a third-party device (slave):

Jumper Settings:

• JP1A: IN (termination resistor connected)

• JP1B: OUT (termination resistor disconnected)

• If a computer is connected as a test device, pin 5 of its DB9 connector must be connected to SCOM1.

6. RS-485 Half-Duplex Wiring Example (Multi-drop)

In a multi-drop network, only the nodes at the ends of the bus need termination resistors. JP#A for intermediate nodes should be set to OUT.

VI. Diagnostics and Maintenance

1. ID Chip Identification

The JA connector on the IS200SSCAH2A board features a read-only ID chip storing the following information:

• Board serial number

• Board type (IS200SSCAH2A)

• Revision number

• J connector location

The I/O pack reads this information during startup and compares it with expected values. If a mismatch is encountered, a hardware incompatibility fault is generated, preventing system problems caused by incorrect configuration.

2. Common Troubleshooting

3. Maintenance Recommendations

• Periodic Inspection: Check that terminal blocks are securely plugged in and wires are not loose.

• Cleaning: Regularly clean the board to prevent dust accumulation affecting heat dissipation and insulation.

• ESD Protection: Wear a grounding strap when handling the board and store it in anti-static bags.

• Spare Parts Management: Maintain a spare IS200SSCAH2A board to reduce downtime in case of failure.