Page 7.3
PROGRAMMABLE RESISTOR MODULES 40-290/291
pickering
SECTION 7 - MAINTENANCE INFORMATION
Table 7.1 - Test Result Limits For 40-290/291
Resistor
Nominal
Value
Maximum
Value
Minimum
Value
PATH
0Ω
See Note1
See Note1
R1
0.5Ω
0.453Ω
0.298Ω
R2
1Ω
0.955Ω
0.795Ω
R3
2Ω
1.96Ω
1.79Ω
R4
4Ω
3.97Ω
3.78Ω
R5
8Ω
7.99Ω
7.76Ω
R6
16Ω
16.03Ω
15.72Ω
R7
32Ω
32.11Ω
31.64Ω
R8
64Ω
64.3Ω
63.5Ω
R9
128Ω
128.6Ω
127.2Ω
R10
256Ω
257.2Ω
254.5Ω
R11
512Ω
514.5Ω
509.2Ω
R12
1024Ω
1029.1Ω
1018.7Ω
R13
2048Ω
2058Ω
2038Ω
R14
4096Ω
4116Ω
4075Ω
R15
8192Ω
8233Ω
8151Ω
R16
16384Ω
16466Ω
16302Ω
Note 1:
PATH resistance limits are 0.5 ohm to 2 ohm for 8 bit modules, 1ohm to 4ohm for 16 bit channels.
Note 2:
All results in red are taken with the DMM offset to remove the PATH result form the answer
The test should be repeated for each channel of the module.
To aid users to establish test limits the following generic tables should be used for the standard modules. The tables
can be copied to record the results for each channel.
Similar principles can be applied to custom modules, if guidance is needed please consult your Pickering Interfaces
representative.
Accuracy limits are dependent on the tolerance of the resistor fitted and the changes in path resistance. For the
40-290 the measured value is:
(PATH -.05 to -0.2Ω)+ (Nominal resistance ± tolerance)
To eliminate the variability of the PATH result the DMM has been nulled to remove it from the subsequent
measurements. The PATH resistance uncertainty assumes the reed relay path used to switch the resistors has a
minimum contact resistance of 0.05Ω and a maximum of 0.2Ω. A typical value is 0.1Ω.
Table 7.1 shows the generic limits for standard modules.
