Cement works installs distributed micro control with 56 inputs
Cement works installs distributed micro control with 56 inputs
Operations room at Blue Circle's Mason Works m Ipswich, UK
Public address cabling cos...
Cement works installs distributed micro control with 56 inputs
Operations room at Blue Circle's Mason Works m Ipswich, UK
Public address cabling costs cut with a microprocessor at every speaker Public address with a microprocessor at every speaker has been developed by M L Engineering. It is intended to be used mainly on oil rigs where cabling costs are heavy. Eacl, speaker in the Orator has an Intel 8085 microprocessor and is linked by two, or three pairs of low-power cables to a central controller. The first wire is for data communications. It uses the RS232 protocol. The second is the audio cable carrying voice and/or music from the central controller. The final pair is optional. It carries power for the speaker. The alternative is local power for the speakers. The microprocessor monitors the data line. Each has its own address for which it waits. This means that calls can be made on a blanket, zonal or individual basis. Four bits are used to set the volume level at one of 16 positions. There is an audio input at each speaker which can be enabled by the central unit. It allows a microphone to be plugged in by someone at the speaker to talk to the operator. There is a selftest facility whereby a tone is generated at the speaker and
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is picked up by the audio input for the operator to check that the speaker is working. M L Engineering plans a database to be included. It could be used in an emergency on an oil rig, for example. The operator presses the 'lifeboat' button and the lifeboat crew is alerted in their quarters and by the names of duty personnel.
Distributed microprocessor control has been installed in cement grinding mills in Ipswich, UK. The £35 000 system looks after clinker and gypsum feeds into two mills. Production rates are typically 70 tonnes/h of Portland cement and 35 tonnes/h of Ferrocrete. Built by Turnbull control systems, the system has 18 TCS 6350 singleloop controllers, with 40 analogue inputs and 16 digital inputs. There is a central control with a colour graphic display. Dual floppy disc drives come with the display which can give four group, four mimic and three short term analogue trend channels and point displays. Each of the group displays can show the current condition of up to 16 control loops or variables at a time. These include the tonnages of material entering the plant, air flows, pressures and mill bearing tern peratu res. Control loops, measured-only points, digital inputs and digital outputs can be intermixed. The operator can change instrument setpoints, control modes and outputs from the central display. The system's central supervisor communicates with the modules via an RS232 serial bus and can thus be located at up to 1000 m away. Local instruments use 16-bit microprocessors with selfdiagnosis.