Yes , SURT20KUXI UPS does support modbus RTU by using AP9622 card. if the Customer wants to use the Modbus RTU for monitoring SURT20KUXI UPS, then the following need to be done:
Customer needs to remove the NMC card from the UPS if he does not want to use the SNMP for monitoring the UPS on the network.There are options available to monitor the UPS via both SNMP and Modbus RTU with additional parts.
Customer needs to purchase AP9622 card + RS232 to RS485 Converter(powered converter).
Install AP9622 card in SURT20KUXI UPS smart slot to configure Modbus, and Modbus RS485 output can be taken from the converter(RS232 to RS485)