Why do valve amps sound "better"? Distortion, its that simple. In fact you can design valve amps and remove most of the distortion they tend to have and they then loose all of that warmth that audiophiles claim makes them better. However the truth of it is that the warmth is simply a distortion imperfection in […]
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DC Motor Types
DC Brushed Motors The original DC motor and still the best suited for many applications. You get bags or torque by giving it current (they develop a maximum torque when stationary, linearly decreasing as speed increases). Brushed DC motors generally have lots of commutators. This means they are often superior for low RPM […]
Modbus Apps
Free sourceforge.net/projects/qmodmaster/ Nice interface but only works with single register values (no float, ASCII strings etc support) https://github.com/SciFiDryer/ModbusMechanic GUI tool for reading and testing MODBUS TCP and RTU instruments. https://www.scadacore.com/tools/programming-calculators/online-hex-converter/ Handy for converting values Paid simplymodbus.ca/RTUmaster.htm Poor operation in Windows 7 but does actually work and does support multi register values so actually a very handy app and […]
Function 16 Write Multiple Registers
Modbus RTU Function 16 'Preset Multiple Registers' To write 3 words (48 bits) to 3 consecutive registers you send the following: Byte 0 Modbus Device Address (1 to 247) Byte 1 Function Code / Message Type (0x10) Byte 2 Start Register Number (high byte) Byte 3 Start Register Number (low byte) Byte 4 Number of registers to write(high byte) […]
Function 06 Write Single Register
Modbus RTU Function 06 'Preset Single Register' To write a word (16 bits) to a register you send the following: Byte 0 Modbus Device Address (1 to 247) Byte 1 Function Code / Message Type (0x06) Byte 2 Register Number (high byte) Byte 3 Register Number (low byte) Byte 4 Data0 Byte 5 Data1 Byte […]
Function 03 Read Holding Registers
Modbus RTU Function 03 'Read Holding Registers' To read a word (16 bits) from a register you send the following: Byte 0 Modbus Device Address (1 to 247) Byte 1 Function Code / Message Type (0x03) Byte 2 Register Number (high byte) Byte 3 Register Number (low byte) Byte 4 Data Length (high byte, specified […]
Modbus Comms General
Resources modbus.org Modbus Application Protocol Describes function codes modbus.org Modbus over Serial Line Specification and Implementation Guide Register Addressing The Modbus register number should really be thought of as an offset rather than an address, as different vendors can use different register addressing schemes. Firstly registers may start from 0 for some devices and 1 for others. The register addressing […]
Modbus TCP/IP
Resources Acromag Introduction To Modbus TCP/IP Has a good explanation of how a RTU serial packet is transferred over TCP/IP modbus.org Modbus Messaging On TCP/IP Implementation Guide Simply Modbus TCP Page Open Modbus/TCP Specification
USB HID Report Descriptors
USB Org resources The full spec and downloadable tables etc can be found here (Device Class Definition for HID). Get the 'HID descriptor tool' from the same page to help create descriptors – very handy!!! Overview A USB HID Report Descriptor is requested by a USB host from a USB device. It tells the host […]
Breadboard
Capacitance between breadboard contacts EEVblog Dave answered this question in the episode here. The quick answer is that for a pair of 5 contact strips next to each other the capacitance between them was close to 2pF across a range of difference boards. Jumping a strip, so you leave an empty one in the middle, halved the capacitance. […]