ADLINK NuDAM-65xx Communication Module Networking and Configuration Guide

Typical Troubleshooting Table

Possible causes and solutions for the fault phenomenon

Unable to find any module converter not powered on or baud rate mismatch; Bus polarity reversed; ND-6520 power supply and serial port connection inspection for signal distortion caused by unconnected terminal resistor; Confirm that the host COM port parameter is 9600, N, 8,1； Measure the voltage difference between DATA+and DATA - with a multimeter (around 200mV when idle)

Specific address no response address conflict or module not initialized; Short circuit the DEFAULT * pin separately to the module before releasing it, attempt communication with address 00, and reset the new address

The communication is intermittent and the bus is too long or has too many branches; No terminal resistor added; Poor grounding of the shielding layer shortens the bus and increases the number of repeaters; Add a 120 Ω resistor at both ends; Improve grounding and use shielded twisted pair cables

ND-6521 transparent transmission failed without opening data gate (non address mode); Delimiter setting error; RS-232 device baud rate mismatch sending&Addr810 opening door; Use~AddrD to read the current delimiter; Using% Reconfigure RS-232 baud rate

The watchdog accidentally triggered the host to not send on time~* *; If the timeout value is set too small, extend the timeout time or disable the watchdog (~Addr20000), check the feeding loop of the host program

Expansion and upgrade suggestions

For ultra large scale systems with more than 256 nodes, multiple RS-485 subnets can be divided, with each subnet bridged to another bus by an ND-6521, or hierarchical management can be achieved using an Ethernet to RS-485 gateway. However, the NuDAM native protocol is based on ASCII and has limited efficiency. If there are too many nodes, it is recommended to upgrade to Modbus RTU or CAN bus.