Serial Port Expansion and C3437 Communication Board Requirements

Issue

A user sees up to 12 serial ports available in the Sage RTU 2400 GUI web interface and can configure ports 9–12, even though only one C3437 serial expansion board is installed. This leads to confusion about whether an additional C3437 board is required to enable those ports.

Product

• Sage RTU 2400
• C3438 DB9 XT Serial Interface Board
• C3437 Serial Communication Expansion Board

Environment

• Sage RTU 2400 with one (1) C3438 DB9 XT board installed
• One (1) C3437 serial expansion board installed
• Serial port configuration performed using the Sage RTU 2400 Web Interface (GUI)
• Firmware versions earlier than K5 and firmware K5 or later

Cause

The Sage RTU 2400 graphical user interface (GUI) always displays all 12 serial ports, regardless of whether the physical serial communication hardware is installed.

Each C3437 serial communication expansion board provides only four (4) additional physical serial ports. If a C3437 board is not installed, the RTU cannot perform serial communications on those ports even though they appear configurable in the GUI.

Resolution

Yes, an additional C3437 serial communication expansion board is required to enable the extra serial ports.

Each C3437 expansion board supports only four (4) serial ports.

• When installed as the first serial communication expansion card, the C3437 provides serial ports 5–8. Its ribbon cable must be connected to the designated side of the C3438 DB9 XT card.
• When installed as the second serial communication expansion card, the C3437 provides serial ports 9–12. Its ribbon cable must be connected to the opposite side of the C3438 DB9 XT card.

The jumpers on the C3437 cards must be configured correctly to identify which card is installed as the first and which as the second expansion board.

The Sage RTU 2400 GUI always displays all 12 serial ports. However, if the corresponding serial expansion hardware is not installed, the RTU cannot communicate using those ports.

There are important firmware considerations:

• Firmware versions earlier than K5
  Assigning a protocol to a serial port without installed hardware and rebooting the RTU may cause the unit to enter a reboot loop. Recovery requires waiting for the RTU to enter Safe Mode and removing the invalid serial port configuration.
• Firmware K5 and later
  These versions detect when serial hardware is not present, prevent the serial protocol task from starting on that port, and display a warning message on the serial User Interface console indicating that a protocol is assigned to a port without installed serial communication hardware.

In summary, an additional C3437 serial communication expansion board is required to enable ports 9–12, and upgrading the RTU firmware to the latest supported version is strongly recommended.

Released for: Schneider Electric Malaysia