Features and Benefits

• ADDC™ (Automatic Data Direction Control) RS-485 data control
• Auto baudrate sensing
• RS-422 hardware flow control: CTS, RTS signals
• LED indicators for power and signal states
• RS-485 multidrop operation, up to 32 nodes
• 25 KV ESD surge protection
• 2 KV isolation protection (A53)
• Built-in 120 Ω termination resistors

Introduction

The Transio A52 and A53 are smart RS-232 to RS-422/485 bi-directional serial converters that come with all of the great technical specs that Moxa is known for. This includes data direction control built into the hardware for both the RS-422 and RS-485 interfaces, LED indicators for power and signal states, and surge protection and isolation protection. The last two features take care of some of the major problems faced by serial communication connections in industrial environments.

Serial Connection Problems in Industrial Environments

Serial communication and reliability can be adversely affected in a hazardous industrial environment. The wiring associated with serial communication devices could be surrounded by power lines, motors, or equipment that produces static electricity. If this is the case, the serial devices could be damaged by sudden surge waves produced by this type of equipment. In this situation, surge protection that uses TVSS (Transient Voltage Surge Supression) is the solution.

When two serial devices are directly connected, but separated by a long distance, the unbalanced ground voltage could cause serious damage. Unbalanced ground voltage between two serial ports forms a "ground loop," introducing a large current between the two pieces of serial equipment. In fact, the current could be so lare as to damage the equipment beyond repair. In this situation, the solution is to use isolation protection to provide complete isolation for both communication ports.

What is Surge Protection?

Surges are high amplitude pulses that last only a few millionths of a second in duration. They can be caused by heavy-duty equipment, power lines, short circuits, or large motors. A surge suppressor has the ability to absorb the high energy instantly and effectively to prevent the connected devices from being damaged.

Port Power Dissipation

When installing a TCC-80 converter, it is important to pay attention to power consumption, RS-232 cable length, and RS-422/485 transmission distance. In general, the TCC-80 obtains 50 mW from the power source. Standard PC COM ports can provide 70 to 90 mW of power if the TxD, RTS, and DTR lines are connected. Moreover, the RS-232 cable should be shorter than 15 m (@ 9600 bps) to ensure that less power is lost from the host/device to the TCC-80. The remainder of the supplied power is used for transmitting the RS-422/485 signal.

What is Isolation Protection?

Electrical isolation is achieved by using a photo coupler to transform an electric signal into light, and then retransform the light back into an electric signal on the other side of the isolator. In this way, the two electric circuits are completely isolated from each other.