You can choose an RS-232 Only Controller Card which enables you to gang switch via the manual toggle switch or with serial commands as well as an RS-232/Ethernet (SNMP) Controller Card which enables you to switch the chassis from anywhere via an RS-232 or IP connection. If you want to extend RS-232/IP control to a second daisy-chained Pro Switching System chassis order the SNMP Expansion Controller Card. This enables you to send hardware control signals and control the daisy-chained system with RS-232 messages through the RS-232/Ethernet (SNMP) Controller Card. Secure and fallback switching. For fail-safe operation all the cards (except those noted) use proprietary latching or micro-mirror relay switching technology- which means data can continue to pass through even if the power has been cut off. Because the cards perform Layer 1 switching the system operates independently of data rates protocols formats or signal levels. The non-latching fiber cards fall back to a Port C (chassis) to Port A connection when the power fails. When power is restored the non-latching switch card reconnects Port C to the originally selected port (A or B). These types of cards are typical when you want a fallback or failover connection during power outages. Each chassis also has a keyed switch so you can enable/disable manual switching from the front-panel toggle switches. Control power. To power your chassis order one or two external power supplies and the power adapter card. For backup power add a Redundant Power Supply Card. Ordering Instructions First order the chassis. Pro Switching System 2U 18-Card (SM260A).Next order the power supply. Redundant Power Supply Cards (requires two chassis slots) 100- 240-VAC Input (SM261A-VAC) Or AC External Adapter Cards (requires one chassis slots) (SM261A-CARD) AND 120- 240 VAC External Power Supply (two for redundant power) (SM961A-PS).then select a Controller Card. RS-232/Ethernet (SNMP) (SM262A) SNMP Expansion (SM264A).next choose your A/B Switch Cards. DB25/RS-232 (SM265A) DB25/RS-530 (SM266A) RJ-45 CAT6 (SM269A) For empty slots order. Blank Panel Front or Rear 2U (SM279A-BLNK).