Continuous Alarm message to DCS from MicroSCADA COM500

The brief Details of the System: The MicroSCADA 9.3 system installed in Ruwais (United Arab Emirates) "Takreer RRE & RRW" project. We have total 40 substations and one CCB(Central Control Building).Each substation is having the Hot stand by ICUs with MicroSCADA 9.3 version in it and each substation ICUs communicate with switch gears and other devices over IEC61850 and Modbus etc. In CCB we have MicroSCADA servers(HP servers with 1TB hard disk).All 40 substations are inter connected in a fiber optic ring network and connected to CCB servers. All 40 substations data is mirrored to CCB servers. From some substations some data(Eg. UPS , some Motors signals) we are sending to Yokogava DCS system over Modbus using COM500.

Problem: From one substation an alarm(UPS input circuit breaker is Open) is generating continuously in DCS system. But as actual the alarm is not generating(Circuit breaker is not opening) in the field and it is showing normal in the Local substation ICU MicroSCADA system. But in the DCS it is showing continuous alarm(Alarm and Normal, Alarm and Normal and so on...)

The data is going from substation ICU to DCS system over Modbus using COM500 in MicroSCADA system. And when I kept the particular signal in Manual mode in Object navigator and simulating the signal as normal condition. Then DCS is not receiving any alarm message from that particular Substation ICU. But if I put that particular signal in Automatic mode, then the DCS is receiving the continuous alarm message again. But at that moment in local substation ICU MicroSCADA is not showing any alarms in the alarm list and in the graphic page.

Please let me know how to trouble shoot where the problem is.Whether it is in COM500 or in DCS side prblem?

Note: Right now I am not in the site.I am going to site by next couple of days to solve this issue.This problem is reported by the end customer over phone.