What this part is and what it does
The Siemens 6AG1640-0AA00-2AX1 is a SIPLUS S7-200 TD 400C text display, based on the standard 6AV6640-0AA00-0AX1 with conformal coating applied. It provides a 4-line by 24-character STN black/white readout with a membrane keyboard that includes 15 configurable system keys. Communication is over a single RS 485 MPI interface at up to 187.5 kbit/s. The front achieves IP65 and NEMA 4, 4x, and 12 when properly installed; the rear is IP20.
How it fits versus a graphic HMI replacement
The 6AG1123-2DB03-2AX0 is a 4.3-inch TFT graphic touch panel with PROFINET and Ethernet — not a functional substitute for this text display. The 6AG1640-0AA00-2AX1 has no touchscreen, no Ethernet, no color display, and runs on MPI only. Panel cutout dimensions differ, and the software environment (MicroWin vs. WinCC Basic TIA Portal) is incompatible. If you need a graphic upgrade, rewiring both the bus and the panel cutout is required; this part is a drop-in replacement only for existing TD 400C installations.
Physical and environmental considerations
Depth is 31 mm; front height accommodates the 4-line display. The membrane keyboard is alphanumeric with dedicated system keys — no touch layer. Supply is 24 V DC. Mounting uses the standard TD 400C panel cutout; ensure the front seal is compressed for NEMA 4x rating.