Documentation for ut70d multimeter communication protocol. 



Copyright (c) 2010 Peter Popovec

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

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but WITHOUT ANY WARRANTY; without even the implied warranty of
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USA.



Cable pins:

		RS232 name
1 NC		Carier detect
2 green		RX
3 white         TX
4,6 orange	DTR(4),DSR(6)
5 yelow		GND
7,8 blue	RTS(7),CTS(8)
9 NC		Ring indikator


IR head  

on head IR transmitter and IR receiver can be found. Cable get out  from
head on side of IR receiver



Communication:

Send  one byte 0-127, get echo of this value

For value 128 to 150  response paket can be received:

Paket format:
0 = echo from command 
1 = mode (rotary switch position+subfunction by yellow button)
2,3,4 bit mapped fields, see bellow,

n-2 checksum 
n-1 0xa0 - end of paket


checksum calculation, because UNI-t doc is very difficult to read. (what
is bit 8 in Uni-T doc ? ). 

Based on experiments and Uni-T doc following algorhithm can be used to
check paket:

1. X=0
2. X = X XOR byte[Y] iterate Y  from 0 to n-3
3. X[bit4] = X[bit4] xor X[bit6]
4. X[bit5] = X[bit5] xor X[bit7]
5. clear X[bit6],X[bit7]
6. X -= byte[n-2]
7. X += 0x22
8. X==0 ?  paket ok.
 

byt 1  MODE
-----
F8 1111 1000  V~
F0 1111 0000  V=
E8 1110 1000  mV
E0 1110 0000  R/C
E1 1110 0001  F
D8 1101 1000  Dio
A8 1010 1000  A=    
A9 1010 1001  A~
B0 1011 0000  mA=
B1 1011 0001  mA~

byt 2  RANGE and UNITS 
-----
bit 7  always 1 ?
bit 6  manual/auto
bit 5,4,3 range ..
bit 2,1,0 
	0 = F-capacitance, 1=? 2= V,A,OHM 3 =? 
        4 = Hz frequency, 5 = %  6= ? 7 = ?


byt 3 
-----
7 always 1 ?
6 "REC"
5 always 0 ?
4,3	00 - none 01 MAX 10 MIN  11 AVG
2 1=beeper on 
1 always 0 ?
0 always 0 ?


byt4  binary maped:
----
7   always 1 ?
6   always 0 ?
5   1 = low bat
4   1 = +    0 = -
3   1 = overflow (0L on display)
2   1 = Hz   0 = no Hz
1   always 0 ?
0   1 = hold 0 = sample



Example response pakets:


 
128 reply paket len  11			ADC readimg SUM1 in FS970X *Direct reading sum1
80 F0 82 80 80 80 A0 8E 90 5E 0A 
129 reply paket len  11
81 F0 82 80 80 80 A1 B8 80 3C 0A 
130 reply paket len  11			ADC readimg SUM2 in FS970X *direct reading sum2
82 F0 82 80 80 80 A2 88 80 4C 0A 
131 reply paket len  11
83 F0 82 80 80 85 B7 BE 80 2F 0A 
132 reply paket len  11			*positive peak
84 F0 82 80 80 8A B7 BE 80 27 0A 
133 reply paket len  11
85 F0 82 80 80 A0 87 B4 80 36 0A 
134 reply paket len  11			*negative peak
86 F0 82 80 80 A0 87 B4 80 39 0A 

135 reply paket len  15
87 F0 82 80 80 80 80 80 80 80 80 80 80 27 0A *UNI-T doc  ktb and ksg (check FS900X doc)
136 reply paket len  15
88 F0 82 80 80 80 80 80 80 80 80 80 80 2C 0A 

137 reply paket len  12
89 F0 82 80 80 3F 30 33 32 33 58 0A 	*curent displey read

138 reply paket len  8
8A F0 82 80 80 81 4B 0A   <<bargraph read  (value 81, byte 5, 80=0 A8=40=max)

139 reply paket len  12
8B F0 82 80 80 3E 36 3B 33 35 5E 0A 	*dual display read
140 reply paket len  12	
8C F0 82 80 80 3F 30 33 32 33 55 0A 
141 reply paket len  12
8D F0 82 80 80 3F 30 33 32 33 54 0A 
142 reply paket len  12
8E F0 82 80 80 3F 30 33 32 33 53 0A 
143 reply paket len  12
8F F0 82 80 80 3F 30 33 32 33 52 0A 
144 reply paket len  12
90 F0 82 80 80 3F 30 33 32 33 51 0A 
145 reply paket len  12
91 F0 82 80 80 3F 30 33 32 33 50 0A 
146 reply paket len  12
92 F0 82 80 80 3F 30 33 32 33 4F 0A 
147 reply paket len  12
93 F0 82 80 80 3F 30 33 32 33 4E 0A 
148 reply paket len  12
94 F0 82 80 80 3F 30 33 32 33 4D 0A 

149 reply paket len  7
95 F0 82 80 80 39 0A 

150 reply paket len  12
96 F0 82 80 80 3F 30 33 32 33 4B 0A 


Summary: 5 paket types can be received:

128 to 134  11 byte response 

135,136     15 byte response - unkown data

137,139-148,150 12 byte response

138 8 byte response		
  bargraph read (byte 5  values 80-A8 = 0-40), 
  on real bargraph for value 0 firs position is active, for value 1  two
  bargraph "positions" is signalized etc ..  for 40 all 41 bargaph positions
  is signalized 

149 7 byte response




151 to 159: only echo can be received

160 echo can be received, switch "autorange" on
161 echo can be received, multimeter "RANGE" button
162 echo can be received, unknown fcion (*UNI-T doc: Hz button .. but this not work) 
163 echo can be received, multimeter "Hz" button
164 echo can be received, unknown fcion (*UNI-T doc: Hold button .. but this not work) 
165 echo can be received, multimeter "Hold" button
166 echo can be received, unknown fcion (*UNI-T doc: REL button .. but this not work)
167 echo can be received, multimeter "REL" button
168 echo can be received, disable "MAX/MIN"
169 echo can be received, multimeter "MAX MIN" button
170 ??	(*UNI-T doc: Peak key, untested)
171 beep on  (untested) (*UNI-T doc: Peak key, untested)
172 ?? (*UNI-T doc: Select key, untested)
173 AC-DC-Cap (untested) (*UNI-T doc: Select key, untested)

174..207 echo only
208,209 (UNI-T doc Read and write EEPROM - untested)

210-255 only echo

---------------------------------------------------------------------------------


Send 0x89,  get 12 byt response:

byt 0 (0x89) 


byt 5,6,7,8,9  - display characters
-------------
byt 10 - checksum
------
byt 11 
------
Always 0x0a ??


Send 0x8A
get 8 byt reponse


Send 0x9B
 12 byt response




range     range  unit  display  multiply to ohm
800 ohm   0        2   xxx.x   *1
8 kohm    1        2   x.xxx   *1000
80 kohm   2        2   xx.xx   *1000 
800 kohm  3        2   xxx.x   *1000 
8mohm     4        2   x.xxx   *1000000
80mohm    5        2   xx.xx   *1000000

800 nS    6        2   xx.xx

Warning, on range switch from 800ohm to 8kohm, some wrong display
data can be sampled. Example pakets:

R Manual 0 2 _ _ _ _ SAMPLE _ +<3 0 > <3 0>  810.3
[89 E0 C2 80 80 3F 38 31 30 33 60 0A]
R Manual 0 2 _ _ _ _ SAMPLE _ +<3 0 > <3 0>  810.3
[89 E0 CA 80 80 3F 38 31 30 33 58 0A]
R Manual 1 2 _ _ _ _ SAMPLE _ +<3 1 > <3 1>  8.103 << wrong !!! 
[89 E0 CA 80 80 3F 38 31 30 33 58 0A]
R Manual 1 2 _ _ _ _ SAMPLE _ +<3 1 > <3 1>  8.103 << wrong !!! 
[89 E0 CA 80 80 3F 30 38 31 31 56 0A]
R Manual 1 2 _ _ _ _ SAMPLE _ +<3 1 > <3 1>  0.811
[89 E0 CA 80 80 3F 30 38 31 31 56 0A]
R Manual 1 2 _ _ _ _ SAMPLE _ +<3 1 > <3 1>  0.811

To get "stable" output for computer, some workaround is needed. This is
like "range" bits is changed before display output is changet. This is
also true for multimeter display, but this can be ignored due display
"blank". This blank is not signalled in data communication ? 

 


                               multiply to pf
8   nF    0        0   x.xxx   *1000  	
80  nF    1        0   xx.xx   *1000
800 nF    2        0   xxx.x   *1000
8   uF    3        0   x.xxx   *1000000
80  uF    4        0   xx.xx   *1000000
800 uF    5        0   xxx.x   *1000000