Difference between revisions of "RadioShack 22-812"

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{{Infobox multimeter
{{Infobox multimeter
| image           = [[File:radioshack_22_812_angle.jpg|180px]]
| image           = [[File:radioshack_22_812_front.png|180px]]
| name             = RadioShack 22-812
| name           = RadioShack 22-812
| status           = supported
| status         = supported
| source_code_dir = radioshack-dmm
| source_code_dir = serial-dmm
| counts           = 4000
| counts         = 4000
| categories       = CAT II (600V)
| categories     = CAT II (600V)
| connectivity     = RS232 (standard DB9 connector)
| connectivity   = RS232 (standard DB9 connector)
| measurements     = voltage, temperature, current, resistance, capacitance, continuity, diode, logic, frequency, hFE
| measurements   = voltage, temperature, current, resistance, capacitance, continuity, diode, logic, frequency, hFE, duty cycle, pulse width
| features         = autorange, data hold
| features       = autorange, data hold, min/max, dBmW (600Ω)
| website         = NA
| website         = [https://www.radioshack.com/search/softwareResults.jsp?kw=22-812 radioshack.com]
}}
}}


The [https://www.radioshack.com/search/softwareResults.jsp?kw=22-812 RadioShack 22-812] is a 4000 counts, CAT II (600V) handheld digital multimeter with RS-232 connectivity.
The '''RadioShack 22-812''' is a 4000 counts, CAT II (600V) handheld digital multimeter with RS-232 connectivity.


It is no longer sold under this part number, and for a while, it appeared to have been discontinued. RadioShack does sell a visually identical multimeter, the [https://www.radioshack.com/product/index.jsp?productId=12988573 RadioShack 22-039]. It is not yet clear if the 22-039 is the same device as the 22-812.
It is no longer sold under this part number, and for a while, it appeared to have been discontinued. RadioShack does sell a visually identical multimeter, the [https://www.radioshack.com/product/index.jsp?productId=12988573 RadioShack 22-039]. It is not yet clear if the 22-039 is the same device as the 22-812.
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File:Radioshack_22_812_terminal.jpg|<small>Banana sockets connecting to PCB</small>
File:Radioshack_22_812_terminal.jpg|<small>Banana sockets connecting to PCB</small>
File:Radioshack_22_812_fuse holder.jpg|<small>Spare fuse</small>
File:Radioshack_22_812_fuse holder.jpg|<small>Spare fuse</small>
File:Radioshack_22_812_chip.jpg|<small>Chip</small>
File:Radioshack_22_812_chip.jpg|<small>Multimeter IC</small>
File:Radioshack_22_812_calibration.jpg|<small>Calibration pots</small>
File:Radioshack_22_812_calibration.jpg|<small>Calibration pots</small>
</gallery>
</gallery>

Latest revision as of 05:32, 15 December 2012

RadioShack 22-812
Radioshack 22 812 front.png
Status supported
Source code serial-dmm
Counts 4000
IEC 61010-1 CAT II (600V)
Connectivity RS232 (standard DB9 connector)
Measurements voltage, temperature, current, resistance, capacitance, continuity, diode, logic, frequency, hFE, duty cycle, pulse width
Features autorange, data hold, min/max, dBmW (600Ω)
Website radioshack.com

The RadioShack 22-812 is a 4000 counts, CAT II (600V) handheld digital multimeter with RS-232 connectivity.

It is no longer sold under this part number, and for a while, it appeared to have been discontinued. RadioShack does sell a visually identical multimeter, the RadioShack 22-039. It is not yet clear if the 22-039 is the same device as the 22-812.

Hardware

The microcontroller is an unidentifiable plastic blob.

This devices has a standard DB-9 connector at the top, and does not require a special adapter cable. The RS-232 transmitter is optically insulated from the rest of the device. The transmitter uses a separate PCB, integrated into the multimeter's housing. The RS-232 module is powered from the serial port.

Photos

  • Mugshot

  • Device, angle

  • RS-232 connector

  • Holster removed, front

  • Holster removed, back

  • Battery location

  • Opened up

  • PCB removed

  • PCB, front

  • PCB, back

  • Buttons PCB

  • RS-232 module

  • RS-232 transmitter

  • RS-232 PCB, top

  • RS-232 PCB, bottom

  • Banana sockets connecting to PCB

  • Spare fuse

  • Multimeter IC

  • Calibration pots

Protocol

The device periodically sends 9-byte packets at 4800 baud, 8n1. The packet includes a mode indicator, payload and checksum. The payload is a 1-1 mapping of the LCD segments.

Packet structure

Byte 7 6 5 4 3 2 1 0
0 Mode
1 Hz Ohms k M F A V m
2 u n dBm s % hFE REL MIN
3 4D 4C 4G 4B DP3 4E 4F 4A
4 3D 3C 3G 3B DP2 3E 3F 3A
5 2D 2C 2G 2B DP1 2E 2F 2A
6 1D 1C 1G 1B MAX 1E 1F 1A
7 Beep Diode Bat Hold - ~ RS232 Auto
8 Checksum

Segment lettering

  A  
   
F B
   
  G  
   
E C
   
  D  

Mode byte

Value Meaning
0 DC V
1 AC V
2 DC uA
3 DC mA
4 DC A
5 AC uA
6 AC mA
7 AC A
8 Ohm
9 Capacitance
10 Hz (dial set to Hz)
11 Hz (dial set to DCV)
12 Hz (dial set to mA/A)
13 Duty cycle (dial set to Hz)
14 Duty cycle (dial set to DCV)
15 Duty cycle (dial set to mA/A)
16 Pulse width (dial set to Hz)
17 Pulse width (dial set to DCV)
18 Pulse width (dial set to mA/A)
19 Diode
20 Continuity (beep)
21 hFE
22 LOGIC
23 dBm
24 (Unknown)
25 Temp

Resources

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