Parameterization - Siemens Simatic Manual

Fail-safe function blocks for storage and retrieval machines
3.7.2.3 Structure of DIAG
Bit
Description
No.
0 SS1 braking ramp not maintained
Parameterizing error T_RAMP: not an integer
1
multiple of T_SAMPLE
Parameterizing error V_MAX:
3 V_MAX / (T_RAMP / T_SAMPLE) cannot be
represented as integer number
4 T_SAMPLE <= 0
5 MAXTOL_V > V_MAX
6 T_RAMP < 0
7 Reserved
8 Reserved
9 Reserved
10 Reserved
11 Reserved
12 Reserved
13 Reserved
14 Reserved
15 Reserved
3.7.3 Principle of operation
3.7.3.1

Parameterization

1. The actual velocity calculated by the F_SAFE_POS block is interconnected at the
SAFE_V input.
2. In the block, the gradient of the braking ramp is determined using T_RAMP and
V_MAX. To do this, using T_SAMPLE and T_RAMP, the number of cycles is deter-
mined, which is required to brake from V_MAX down to standstill. In each cycle, the
internally calculated maximum permissible velocity is then. correspondingly reduced
by the block.
When parameterizing (assigning parameters) it should be observed that the following rela-
tionships must be able to be represented as integer multiple:
T_RAMP / T_SAMPLE
V_MAX / ramp_cycles
Further, the following relationships must exist between the input variables:
MAXTOL_V <= V_MAX
The permissible value ranges of the individual inputs should be taken from the table describing
the inputs.
The block identifies if not all of the mentioned preconditions are satisfied, and this is signaled as
parameterizing error with the appropriately set DIAG bits.
S7-Distributed Safety/SIMATIC Safety - fail-safe function blocks for storage and retrieval machines
Information regarding the function status and errors of the
block are output here. (also see the table below)
Reset condition
SAFE_V falls below
V_STOP_MONITORING and a positive
edge at ACK
The ratio between T_RAMP and
T_SAMPLE is an integer number
The ratio between V_MAX and the number
of cycles for the braking ramp specified by
T_RAMP and T_SAMPLE is an integer
number
T_SAMPLE parameterized > 0
MAXTOL_V parameterized <= V_MAX
T_RAMP parameterized >= 0
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