ABB AC500-S Safety User Manual page 29

● No detection of wire cross-talk or short circuit to 24 V DC for S-DOs of DX581-S. Why
and how to solve this problem?
The outputs of the DX581-S safety module are decoupled from the connected load. This is
necessary to avoid any influence of connected load on the internal test circuit and, thus,
guarantee high robustness (no occasional trips due to false error detection caused by unex-
pected change of electrical characteristics of the connected load). Therefore, wire cross-talk
and short circuit to 24 V DC can be detected only up to the output clamp of DX581-S safety
output, but not on the attached output wire. In most customer cases, error exclusion due to
output wire isolation or, alternatively, the machine re-start (with proper start-up test proce-
dure implemented in the safety CPU program for given S-DOs to activate them one after
each other) at least 1 per month is often enough. The user may also take other appropriate
actions (e.g., by defining appropriate test periods for the safety function or by reading back
the status of the output wire using a safety digital input) to satisfy their respective IEC 62061
and ISO 13849-1 requirements, if wire cross-talk or short-circuit to 24 V DC shall be imple-
mented.
● Is my safety program OK if not all safety programming guidelines and rules checked
by AC500-S safety code analysis (SCA) rules are satisfied?
SCA tool only checks whether the static safety programming guidelines or rules are fol-
lowed. As such, any errors identified by SCA tool may not necessarily result in machine mal-
function but will require additional argumentation why those exceptions (not fulfilled safety
programming guidelines or rules) are allowed in the given customer safety application case.
The latter may delay the certification of customer safety application program.
● What does built-in power supply in the safety I/O module mean?
It means that no separate power supply module shall be bought for AC500-S safety I/Os.
24 V DC can be directly connected through UP and ZP pins on the terminal unit.
● What is the effect of connecting test pulse of the same type (e.g., T0, T1, T2, T3, etc.)
from one module to the safety digital input channel of another module? Are test
pulses module-specific?
Yes, test pulses are module-specific. As test pulses are module-specific, connecting any test
pulse of the same type from one module and still the same channel on the other module
would cause channel passivation. This kind of connection is not permitted and not recom-
mended.
● Will there be a different delay of safety telegram if the safety module is placed in
another physical slot (communication module or I/O module slot)?
The telegram delay difference can be negligible in such cases and possible difference is far
below 1 ms.
● Is 1oo2 internal safety structure applicable for safety inputs only when we have 2-
channel input?
No, the entire AC500-S hardware system is designed using 1oo2 internal safety structure.
Hence, even when you connect a single input, internally it is split and processed using 1oo2
safety architecture.
● How to interface safety mats/bumpers and safety edges?
Most of the safety mats and bumpers in the market come with ASi-Safety option. With the
help of ASi-Safety to PROFINET/PROFIsafe gateway, you can connect such signals to
AC500-S.
● Can we use 2-wire transmitters with analog input?
Yes, AI581-S analog module is equipped to handle both 2-wire and 4-wire transmitters.
● What is the ON time of a test pulse in DI581-S/DX581-S modules? How often is it
repeated?
Test pulse terminal clamps provide 24 V DC signal for monitoring passive sensors with test
pulses. This test pulse signal is switched off for a fixed time (1 ms) to LOW state. This is
valid for both DI581-S and DX581-S module. The test pulse repeats every 58 ms for DI581-
S and every 27 ms for DX581-S module on each test pulse channel.
● How often is the safety output OFF when the detection feature is made ON in DX581-S
module?
If the detection is enabled, the output of the DX581-S safety module is tested every 55 ms.
Be aware, that the test pulse of the internal main switch can also be observed on each
output. The main switch test pulse cannot be disabled and is always present. Its duration is
slightly below 1 ms in the worst-case (if the output current is 500 mA) and is almost not
visible in the best-case (if the output current is below 50 mA).
2020/06/19 3ADR025091M0208, 12, en_US
Overview of AC500-S safety PLC
FAQ - AC500-S safety PLC
29