HONEYWELL SDI-1624 CC V1.2 DIGITAL INPUT

One PM point has 127 flag register, 80 real register, 4 time register, and 16 string register, so even developing a large sequential control program with one PM point is sufficient. The control programs for the seven gas furnaces in our factory’s gas production system were developed using it. Here, I would like to mention some safety issues encountered during the use of the gas furnace control programs developed using it. Our new gas stove was put into operation in May 2002 and the control program of the gas stove performed normally from August 2003, with no issues found. In mid August, there was a sudden power outage in the entire factory, and the UPS of the gas production system also malfunctioned. The inverter could not operate normally, and the battery could not supply power normally, causing operators to be unable to shut down the boiler normally. After 10 minutes, the system called and the operator noticed that some on-site solenoid valves were operating (not in a safe shutdown state), which could cause gas to enter the air pipeline and cause an accident. After our inspection, it was found that although the entire system was powered off (including UPS), the applications within HPM were still running because HPM’s power box had a small battery that could still provide HPM with power for a long period of time. As a result, the input and output cards cannot be maintained in the originally designed power outage safety state. Of course, this is related to our inadequate consideration when developing programs, but it does need to be taken seriously by our developers. Afterwards, we made improvements to the development program and external circuits to avoid the occurrence of this phenomenon.