Please see the Manual of <SIMATIC S7-300 S7-300 Automation System Module Data>,at the following link.http://support.automation.siemens.com/CN/view/en/8859629
I have two question:
1.Page373 It is technical data about 6ES7331-7PF01-0AB0,the max input cable length is 200m, what is the range of the diameter for the conductor?
As Darius replied for this subject, it's related to current. For analog channels, 0.5 mm2 is fine. Do not use too small wire sizes in order not top trigger wire break message. see page 286 of module data.
2.Page434, It is technical data about 6ES7332-5HF00-0AB0,the load impedance for current outpout is max. 600 Ω at CMV < 1 V. Why is it limitted the CMV(between S- and MANA )<1V? What can i do,if the CMV>1V?
"CMV" is the Common Mode Voltage which is The voltage common to all terminals of a group, measured between this group and any reference point (usually ground potential.)
You should keep CMV within permissible limits. if not you will have a diagnostic message of Common mode error
The cause of this message is: Potential difference CMV between inputs M and the reference potential of measuring circuit (MANA out of limits).
To remedy: Connect M- with MANA
Hope this helps.