Siemens LZN705JX0073 C98043-A7002-L4 Processor Board

The LZN705JX0073 is a high-performance printed circuit board manufactured by Siemens, corresponding to order number C98043-A7002-L4 and alternative C98040-A7002-C1-03. It is designed as a central processing or communication board for SINUMERIK 840D CNC systems and SIMATIC S7-400 PLC racks. The board handles real-time motion calculations and high-speed I/O scanning.

Specifications

• Processor: 32-bit RISC CPU @ 200 MHz with floating point unit

• Memory: 8 MB SDRAM, 4 MB Flash (program backup)

• Communication Interfaces: 2x PROFIBUS DP (MPI/DP), 1x Ethernet (10/100 BaseT), 1x RS232

• I/O Capabilities: 16 digital inputs + 16 digital outputs (24 VDC, 0.5 A) via on-board connectors

• Bus Interface: P-bus (Siemens backplane) for S7-400 rack communication

Functional Architecture

The board operates as a master on the PROFIBUS network, handling up to 125 slave devices. Its integrated motion controller calculates 6-axis interpolation at 1.5 kHz update rate, making it suitable for synchronized multi-axis machinery. The board’s flash memory retains user program and parameters even after power loss, with an optional battery backup for real-time clock.

Diagnostic Features

Seven LED indicators display board status: RUN, STOP, BUSF (bus fault), SF (system fault), BF (battery fault), FORCE, and LINK (Ethernet). An onboard DIL switch sets MPI address, baud rate, and hardware reset behavior. The board can output internal voltage and temperature readings via the backplane for predictive maintenance.

Mechanical and Environmental

Dimensions: 233 mm × 160 mm (double Eurocard format). Weight: 480 g. Operating temperature: 0 to 60°C, humidity 5–95% non-condensing. The board is conformal coated for protection against dust and mild chemicals. It requires a 5 VDC supply from the backplane (1.2 A typical) and a 24 VDC load supply for outputs.

Typical Use Cases

Deployed in CNC machines (milling, turning, laser cutting) as well as high-end plastic injection molding machines. The board is also used in retrofitting projects where legacy Simatic controls need CPU upgrade. Replacement parts must be ordered with exact MLFB: 6ES7 400-2XX-... compatible variants.