Banner Safety Mat Monitoring Modules User Manual

Page 7

Safety Mat Device Checkout - Prior to Module Connection

Before connecting the safety mat to the Module, verify the installation does not exceed the maximum resistance specification. Check the
mat with an ohmmeter to verify that none of the following values are exceeded.

1. Check the leadwire resistance.

a) Keeping track of which wire goes to which terminal, disconnect all 4 wires from the terminal blocks.
b) Measure and record the resistance between the wires going to terminals S11 and S12: ________ (=Ra)
c) Measure and record the resistance between the wires going to terminals S21 and S22: ________ (=Rb)
d) Review the values for Ra and Rb.

If both Ra and Rb
are

Then

Less than 50
ohms

The lead resistance is acceptable for all supply voltages; check the mat resistance next. If it is 50 ohms or
more for either, continue below.

Less than 500
ohms

The lead resistance is acceptable for an AC supply and for a DC supply >20 V. If resistance is acceptable for
your supply, check the mat resistance next. If resistance is not acceptable, lower the lead resistance by short-
ening the leadwires or by increasing the wire diameter. Recheck Ra and Rb.

2. Check the mat resistance.

a) Step on the mat in various locations while taking the measurements listed below.
b) Measure and record the highest observed resistance between S11 and S21: ________ (=Rc)
c) Measure and record the highest observed resistance between S21 and S22: ________ (=Rd)
d) Review the values for Rc and Rd.

If both Rc and Rd are

Then

Less than 10 ohms

The mat and leadwire resistance is acceptable for all supply voltages and the
safety mat checkout is complete.

Less than 150 ohms AND you are using an
AC supply or DC supply greater than 20V dc

The mat and leadwire resistance is acceptable and the safety mat checkout is
complete.

Any other value

If resistance is not acceptable, proceed to the next step.

3. Connect the ohmmeter to the wires to be connected to S11-S12 (Channel A), and note the resistance.
4. Connect the ohmmeter to the wires to be connected to S21-S22 (Channel B), and note the resistance.
5. Perform the following calculation: Rm = (Rc + Rd - Ra - Rb)/2.

If Rm is:

Then

Less than 10 ohms

The mat resistance is acceptable for all supply voltages; the safety mat checkout is
complete.

Less than 150 ohms AND you are us-
ing an AC supply or DC supply greater
than 20V dc

The mat resistance is acceptable and the safety mat checkout is complete.

Any other value

The resistance in the mat is too high for safe operation. Replace the safety mat. Repeat
the mat resistance checkout for the new mat.

WARNING: Safety Mat Resistance Values
Exceeding the maximum resistance

between the monitoring channels (usually due to degradation

of the mat) can result in the increase of response time or complete loss of the sensing function of
the safety mat, when it is stepped on (shorted). This can result in serious injury or death.
Exceeding the maximum resistance within a contact monitoring channel can result in the Module issuing a
stop command (opening the safety outputs) when no person is present.

SM-xA-5A Safety Mat Monitoring Modules

P/N 122364_Web
rev. C