The PIC-DIO RS-485 Digital I/O Interface allows you to connect logic level Digital I/O to an RS-485 network running at 9600 baud. Commonly used with RS-485 capable home automation systems such as the HCS-II and JDS Stargate, it can be used on any Master/Slave 9600 baud RS-485 network. Commands allow for individual bit manipulation and querying as well as byte wide data output to devices like parallel printers or other devices with 8-bit parallel inputs. Control commands are sent via a simple ASCII based protocol:
! DIO4 SDP.Y=X<CR>
will set bit Y to X (0/1)
! DIO6 T DP=Hello Networked World<CR>
will print Hello Networked World on a connected parallel printer
This chip uses a slightly larger PIC (16C63A) than the original Mini-DIO so it has more RAM for a bigger packet buffer. This chip has a 128 byte buffer so long text strings can be sent to it for printing on a printer or any other device connected to it. Note that this chip also has a BUSY input (in addition to the STROBE line) so full handshaking with the printer/connected device is possible, improving the data throughput (Approx 8000 chars/sec). Note that the PIC-DIO can still be used for generic digital I/O in remote locations. Simply add proper buffers to the I/O port to ensure you don’t damage the PIC.
PIC-DIO (Assembled)
A common implementation of the PIC-DIO is hooking up thermal logging printers to an RS-485 network. Control programs can print error logs quickly onto a thermal hard copy record. While many printers have only USB interfaces, many thermal data printers still come with Centronics parallel interfaces.
For complete information about the PIC-DIO, consult the instruction manual. The manual also lists the contents of the kit The PIC-DIO kit has all the parts you need to hook up an old printer to your HCS for detailed logging of events, sensor readings, etc.
All Creative Control Concepts RS-485 Interfaces ship with MAX483E RS-485 transceiver chips for +15kV ESD Protection & Slew Rate Limiting. This ensures the modules can endure surges often induced over long RS-485 cable runs.
Product Information
- Instruction Manual (Acrobat)
- Schematic (Acrobat)
- PIC-DIO Firmware HEX File (v1.1)
[Use a 4MHz 16C63A w/ 3.6864 Crystal]
Change History
- v1.0 - Original Release
- v1.1 - Adds status LEDs, a better serial routine, a network reset command, a slower clock for more accurate 9600 baud, and more.
- v1.2 - Switched to ring buffer for serial port. Short input pulses between network queries are now caught.
