New HIDS Drum Scales!
Click Here to Learn More!The HI 2151/20WC and HI 2151/30WC weight controller parameter setting for scale capacity normally is used to define an upper displayed, weight limit, not an upper weight. If this value were exceeded by 5% an error message of --HI-- would be displayed on the unit display. If you had a communications option, that communications would still transmit the weight reading up to the extent of the analog to digital internal registers. The upper range of weight reading is established by the load cell capacity. Scale capacity sets the upper range of displayed weight.
2151/20 only: If you are configured and communicating over a serial Modbus network the scale capacity has a different meaning. The Modbus network is configured as master/slave architecture with the host being the master and the HI 2151/20WC being the slave. Modbus communications is not available in the HI 2151/30WC weight controller.
Communication is initiated and controlled by the master. The master can read "input registers" and write to "output registers". Modbus holding registers are 16 bits in length. All 16 bits are used for reading and setting discrete status bits. Modbus limits analog values to 12 bits; therefore the upper four bits of analog holding registers are not used. The HI 2151/20WC has a display resolution of 985,000 bits compared with the Modbus 4095 bits. To make the transition, the HI 2151/20WC scales all outputs (host inputs) to a 0-4095 range. Conversely all inputs (host outputs) are ranged from 0-4095 to the appropriate range. The full-scale value used to compute the scale factor is the "scale capacity" that is entered in the calibration menu. For example: if the scale capacity were set to 40950 then the scale factor would be 10 (40950/4095 = 10). For the host to send a Setpoint value of 20,000 lb, a value of 2000 would need to be sent to the HI 2151/20WC.
