Data Exchange with the SM 335
3-38
SM 335 – High-Speed Analog Input/Output Module for the SIMATIC S7-300
6ES7 335-7HG00-8BA1
Common mode error (bytes 8-11, bit 1)
There is an excessive common mode voltage at the analog input. If the common
mode voltage is too high, the SM 335 simultaneously sets bit 2 in the module diag-
nostic byte 1 to “1” and the measured value to 7FFF
H
.
As soon as the common-mode voltage returns to a permissible level, the SM 335
resets the bit. (see also Section 2.2, Connecting the Analog Inputs)
Open wire (bytes 8-11, bit 4)
Bit 4 is set in the channel-specific diagnostic byte for an analog input when a open
wire is detected at that input.
Underrange and overrange (byte 8-11, bit 6+7)
The measured value at the input is checked for violation (overrange: bit 6; under-
range: bit 7). Depending on the direction of the range violation, the SM 335 sets
either the overrange or the underrange bit.
Analog output (bytes 12-15)
The SM 335 sets bits in the channel-specific diagnostic byte for an analog output
when it detects a short circuit or a parameter assignment error at the analog input.
Short circuit on the analog output
7
6
5
4
3
2
1
0
Parameter assignment error
Fig. 3-16
Channel-specific diagnostic byte for an analog output
