SEC402-51 S1 Yokogawa | ESB Bus Coupler Module

Configured for ESB bus master communication in the Yokogawa ProSafe-RS Safety Instrumented System, the Yokogawa SEC402-51 S1 (SEC402-51 ESB Bus Coupler Module) provides the physical interface between the safety control unit and connected safety node units. It supports 128 Mbps I/O module data transmission and a maximum ESB bus distance of 10 m. 

Hardware Specifications

Yokogawa documentation specifies the SEC402 as a 2-port ESB Bus Coupler Module. The upper and lower ESB bus ports can each connect up to 9 units, while the total number of I/O nodes depends on the applicable ProSafe-RS configuration and node expansion package. 

ESB Bus Communication Characteristics

The SEC402-51 S1 operates as an ESB bus master interface. It transfers I/O module data at 128 Mbps and connects safety node units through dedicated ESB bus cabling. Yokogawa specifies a maximum transmission distance of 10 m for each ESB bus connection from the upper or lower port. The module uses two ESB bus paths for connection to safety node units. Therefore, installation must maintain the specified cable routing and distance limits for each bus path. Yokogawa documentation identifies YCB301 as the dedicated ESB bus cable. 

Frequently Asked Questions

Q: What communication speed does the SEC402-51 S1 support?
A: The module supports 128 Mbps for I/O module data transmission.

Q: How many units can connect to the SEC402-51 S1?
A: The supplied specification states a maximum of 9 units on each upper and lower side. The applicable total node count depends on the ProSafe-RS system configuration. 

Q: What is the maximum ESB transmission distance?
A: The maximum specified distance is 10 m for each ESB bus connection.

Field Installation Guidelines

• Install the module in the designated safety control unit slot according to the applicable ProSafe-RS hardware configuration.
• Connect the upper and lower ESB ports using the specified ESB bus cable.
• Keep each ESB bus cable within the specified 10 m maximum transmission distance.
• Route ESB communication cables separately from high-current power wiring where practical to reduce electrical interference.
• Verify connector seating before energizing the safety control unit.
• Maintain cable shielding and grounding according to the Yokogawa installation documentation and site grounding scheme.
• Do not apply an unspecified external supply to the module. The supplied specification identifies current consumption but does not specify a separate field power input.
• Confirm the installed node count against the applicable ProSafe-RS system configuration before commissioning.